5W-40 synyhetic oil in a garden tractor engine.

GLMPA

Member
In my research on the subject,I have come to the conclusion that 5W-40 synthetic engine oil should meet my year around needs in the central midwest.I have a Wheel Horse 520H with 20 HP Onan engine,1989 version. My operators manual suggests 30 wt. or 10W-30. 30 wt will protect above 100 derees farenheit but 10W-30 protects to 80 degrees. Our summers usually exceed this temp. The 5W-40 suggests protection from -30 degrees farenheit to > than 100 degrees farenheit. A thicker oil is also beneficial to the life of the engine during hot weather if I am reading into it correctly. I feel its a no brainer to use 5W-40 year around. What are your thoughts on the matter? Thanks for the input. I am anxious to get multiple thoughts.
 
Following what Onan says is the real no-brainer and they call for straight grade 30W when the lowest temp is never below the freeze point of water.

A multi-grade such as 10W30 is advised when the temps are between Zero degrees F and up to 80 degrees F. The use of 10W30 often means higher oil consumption which can lead to carbon deposits building up in the combustion chamber area.

Oil is the least expensive item for an engine and the easiest to change. So why not follow what the manufacturer advises? Changing your oil twice each year isn't a big deal and it is also good for the health of your engine.
 
With older engines that have run all of their lives on regular oil , take care! Straight synthetic can lead to oil leaking out all over through the seals. The rubber shrinks a little. Use the 50/50 blend stuff. MUCH safer. You have the right idea about the weights but use the blend. Jeffcat
 
I don't run my garden tractor below 15 degrees but I use 15-40 all year round for the last 27 years with no problems.
 
Wrong......

That is a problem from ages ago that no longer exists. Synthetic oil sold today will not damage engine seals.
 
5w40 synthetic is an ideal oil for your onan. I assume your speaking of Rotella or Delo?
I have used Rotella 5w40 in several small engines and it works fantastic.
 
Really Josh? Please tell us how you know to a certainty that it
works fantastic compared to what the manufacturer tells owners
to use. In what way or ways is 5W50 superior to what Onan says
owners should use?

Do you have a testing laboratory at your disposal?. Did you
conduct long term testing to several identical engines using
other grades of oil and then analyze the wear that took place?

Perhaps I have it wrong and you are an oil engineer that is
qualified to make blanket statements such as this. If so, please
let us know.
 
Thanks gentlemen for all the responses. I guess I have been a little leary of using 5w-40/15w-40 in this engine since I have always thought of these 2 blends to be for diesel engines only. But with the info from the Onan engine manual, I thought maybe I could have the best of both worlds in using one of the above. But after your kind thoughts, I see that maybe I should follow the manual guidelines and change my oil in the spring and the fall to be ready for the impending season. I have always wondered if the high mileage engine oil really protects the seals as they state(eg. Valvoline maxlife,etc.)Since this engine is 25 years old I could use these if there is benefit to be had. I believe they make straight 30 wt. and I know they make 10W-30. Thanks again guys, you have all been a good help.
 
You can believe that if you want, but I have seen engines switched over in the last 10 years that suddenly started leaking like a sieve. Switched back to dino and the leaking stopped.
 
I will never use synyhetic oil again. I bought a Chevy Impala LT with a 3.9 and under 15,000 miles on it. When came due for first oil change asked Chevy dealer what to use in that engine and he said to go full synyhetic and thats what I did. In the next three oil changes it used a quart of oil every thousand miles (no leaks anywhere). I went back to conventional oil and it didn't use a drop oil after that and that has been three years ago.
 
I've used nothing but 30wt oil in my Wards garden tractor. I bought it new in 1971. I've never had the engine apart. I did pull the head to reach and remove a mouse nest. I don't use it if its bitter cold. I've been using the snow blower on all the snow fall this month. I use 30wt in it too. I've had it 17 years. I've never liked Tecumseh engines, but the one on the snow blower has been a good one. Hal
a145461.jpg
 
we run 10w30 most everything going thru shop. never had any issues. synthetic is just a thinner based oil. run it more in hydro more than anything else.for just everybody small engine use we don't see where its worth the extra cost . its a mind game again or something new to sell.
 
One of the WORST topics for discussion on forums is OIL. If you really want to know about OIL, then join Bob is the Oil Guy (link below) because that is the only thing under discussion.

You likely have a P-Series Onan engine in your tractor and while the Performer Series is not as dated as the earlier CCA and BF/BG models, it is basically the same technology. The biggest change is the introduction of electronic ignition to the P Series, which did away with the points and condenser. That is hardly what I would call a major re-design. There is no question that the Onan flat twins were a premium quality engine but the fact remains that the entire design prohibited Onan from making them comply with the new emissions standards enforced by the EPA. So in or around 2000, production of the Onan ceased. I know this to be factual because I had a telephone conversation with an engineer at the Linamar plant where Onan and Linamar engines were last built.

The older Briggs and Stratton's, Kohler's, Onan's, Tecumseh's etc were all designed to consume modest amounts of oil between oil changes. Car engines used to be the same way, which is why the service station attendant automatically opened your hood and checked the oil level of your engine every time you pulled in for gas.

In spite of all the wonderful things that modern chemistry has brought to the world of OIL, the fact remains that multi-grade oils are not the panacea for OLD STYLE engines that some people believe them to be. Multi-grade oils are full of "modifiers" that cause the viscosity to change in relation to the temperature of that oil. That is what allows an oil to behave like a 10 weight in cold weather but then behave somewhat like a 30 weight when the engine reaches operating temperature. Essentially, this is a compromise in order to provide the consumer with an all-season oil. However, a compromise is not always the best choice.

I do not claim to be an oil expert. What I do claim is that companies such as Onan, Kohler, Briggs and so forth have spent millions of dollars putting their engines through the most brutal testing possible in order to determine the BEST type of oil to use so that the consumer can get the maximum life from their product. In spite of the existence and extensive use of modern oils, NONE of these manufacturers have gone back into the Operator's Manuals for their engines and moved away from what they originally recommended.

Synthetic oils are renown for having a long life inside modern engines and the manufacturers of these oils tout that extended oil change period as justification for the higher cost of synthetics. The problem with that theory is when the uninformed try to apply it to air-cooled engines that do not have an oil filter. The crankcase is a nasty place for any oil because the old technology engines have much greater clearances then the new technology engines. Raw fuel gets past the rings when the choke is applied during cold starting and so do combustion gases that create acids and bring particulate to contaminate the oil.

In the absence of an oil filter and less than ideal crankcase venting systems, even the best oil will become contaminated to the point of causing a risk to the bearing surfaces. As these bearing surfaces become damaged, the material from them adds to the contamination and a domino effect comes into place. Synthetic oils are great but they have no more resistance to these types of contamination then real oil does. The ONLY solution to this problem is TIMELY OIL CHANGES.

Most manufacturers tell owners to change the oil every 25 hours of use MAX and more often if the engine is being used in harsh conditions. None of the engine manufacturers have swayed from that advice. Those that choose a synthetic oil in order to double the number of hours between oil changes on engines with no oil filter are not doing their engines any favour.

YOU cannot look at engine oil and determine whether it is clean or dirty. Oil will often change colour with heat. Oil filters remove particles as small as 10 microns. ONE micron is equal to one 25,000th of an inch. The human eye cannot even detect particles smaller than 25 microns and one must have excellent vision to see a particle that tiny.

The human eye cannot detect the deterioration of the modifiers added to multi-grade oils that allow them to behave at certain temperatures. The human eye cannot detect acid or fuel contamination in oil, either.

Yes, modern engines love modern oils but modern engines a built using the latest technological advances in metallurgy that allow much tighter tolerances and those tight tolerances call for oils with a 5 weight viscosity in order to assure lubrication to all parts during cold weather starts. There is no such need in old technology engines but there is definitely a need for oils with a consistent viscosity such as straight grade 30 weight oil to help cool these engines and maintain that crucial thin film of oil that keeps metal surfaces from destroying one another.

To me, it all comes down to one thing. I want to get the maximum life out of my old school engines because rebuilding these old engines can be expensive and time consuming. Therefore, it is my belief that the people who made these engines are smarter than I am and when they say I should use straight grade 30W oil in the crankcase and change that oil every 25 hours, then THAT is exactly what I am going to do.

For those who choose to listen to people that come on forums and say that their brother's uncle has used such and such an oil in his engines for the past 25 years...... be my guest. But you should take note that these same people rarely disclose the make and model of the engines nor the history, in their posts. Instead, they just make blanket statements with no real FACTS to support their claims.

This is why I suggest that people go the websites of Kohler, Onan, Briggs etc and READ what those companies suggest to be used in their engines. Now, if you think that you are smarter then all of their engineers, then by all means.... use whatever you want in the crankcase of your engines. Perhaps you will get lucky but perhaps you won't. In the end, it is your money.
Bob is the oil guy
 
That was a great speech, especially the part about being smarter than the engineers that designed and built it.
 
Thanks Tom for the info. I am glad I asked this question on the forum. I feel that I am much better informed and believe that following the manufactuers recommendation is the best thing to do. I certainly do not want expensive repair bills . I will use this unit much more in the summer and the 30 weight oil will give the protection I need. I plan on switching to the 10W-30 in the late fall in case I need to plow snow. In this particular unit it calls for 10W-30 in the transmission. I would be interested in your thoughts regarding conventional vs.synthetic blend vs. synthetic in the transmission. I am assuming you would recommend conventional with oil changes as recommended. I just want to make sure I am doing all I can to keep this unit in the best operational condition as I possibly can. Thanks for your input.
 
The decision between using synthetic instead of conventional oil is often based upon what happens temperature-wise in the area where the tractor is being used.

There is no question that synthetic oils flow much easier when subjected to sub-zero temps and that factor can be very important when trying to start an engine. While it might seem like I am back-tracking here, in fact I am not. It is up to the individual to look at the historical temperature charts where they reside and see whether using synthetic makes good sense during the winter months.

Consistently cold temps that stay at or around zero degrees F or lower would certainly call for the use of a synthetic, not only in the engine but also in the transmission and rear end if they are separate items. Personally, I see no reason to not use the 5W40 synthetic you spoke about in your initial post for the transmission and rear axle and it should be OK all year around.

Now if you were a farmer or commercial operator that used a tractor nearly every day for up to 8 hours at a time, then the frequency of oil change would certainly come into play, as would the best choice of viscosity during the hot part of the summer.

But if you are like most homeowners, then all you put on your tractor is about 50 hours per year. One of the things I advise is the purchase of an hour meter for garden tractors because they keep track of time for you and help you with your maintenance program. These often show up on sale at Harbor Freight and sometimes Northern Tool.

Synthetic oils have also been shown to make an engine run cooler than with regular oil. For example, Amsoil offers a 30 weight straight grade oil designed for air cooled engines. Link below. Naturally, it is more expensive then say... Shell's Rotella T 30W and as always.... it comes down to personal choice.

One of the biggest problems with claims about oils is that it is sooooo very hard to substantiate them to a scientific certainty. Perhaps if a lab were to obtain 200 brand new engines that were all made on the same day at the same engine plant and then run half of them with synthetic and half with conventional oil, there might be some sort of results that could underpin claims of superiority.

Of course, all 200 engines would have to be subjected to identical testing on the same day and every aspect of the tests would have to be identical. I just want to be sure that everyone understands that I am not against synthetic oils nor am I against multi-grade oils.

All anyone has to do is to go to places such as Small Engine Warehouse and price out a replacement engine for their tractor. Compare that cost to that of gambling with something as inane as oil choice because relatively speaking, oil is very inexpensive.

Gear type transmissions, rear ends or trans-axles are pretty forgiving when it comes to oil choice but less so with engines. Engines spin at up to 3600 RPM, often for several hours whereas transmissions etc rotate very slowly with much less demand on the oil. As always, clean oil is the secret to long gear and bearing life. Oil can be badly compromised by water either infiltrating the trans-axle etc by way of loose bolts or bad gaskets as well as by moist air condensing on cold metal.

There are instances where there is so much water in the rear end of a tractor that it freezes solid and prevents the tractor from moving. That situation can also cause the casting to split open.

If you own a tractor, then you should also own the correct Operator's Manual as well as the Parts Manual. Both items are invaluable when it comes to maintaining your tractor in peak condition.
Amsoil small engine oil
 
Tom, maybe you should read some of the posts on the site you suggest we all read. I have been a member for years and Rotella 5w40 is one of the most recommended oils in the small engine forums. There are many oil analysis that support that 5w40 is a great oil for small engine use.
Times change and automotive 10w30 is not really suited for small engine use anymore. Rotella does make a 10w30 that would be well suited for small engine use, but for the best high and low temperature protection, 5w40 is the way to go.
 
I also like the Amsoil small engine oil you link to. I have used that for years in a couple small engines. I'm sure it would work well in an Onan. Lots of zinc and a good additive package that is missing from modern automobile engine oils.
 
With all due respect to you Josh, I wish to point out what I find
perplexing with your reply as it is the same problem I have with
some of the other replies in this thread.


In a nutshell, what you say is "non-specific". Right from the
beginning, this thread has been about what is best for an Onan
engine. Modern engines such as the Honda GX, B&S Vanguard's,
Kohler Command Pro's, Generac's or Kawasaki's are all "small
engines" but their needs when it comes to oil are not identical to
the needs of the old engines such as the Onan.

I am a firm believer in Shell's Rotella T line of oils because I often
recommend that brand for use in the Case/Ingersoll hydraulic
system in the form of 15W40 and also in the trans-axles of those
tractors. However, until the engine manufacturers themselves
come out and state that it's OK to use 15W40 in their old school
engines, I personally will stick with Rotella T in a straight grade
30W.

Both you and I know that an old school engine is not going to fail
instantly just because the owner switches over to 15W40. To
me, the question here is whether the multi-grade is performing
equal to the straight grade oil at all times. There are things that
an oil analysis doesn't tell us but there is no question that it is a
valuable tool. One factor not mentioned is the cost of the
analysis and for those who use small, air-cooled engines this
tool is often too expensive. The other factor is the duty-cycle of
the small air-cooled engine because Joe Homeowner rarely uses
these engines often enough or long enough to justify the cost.

My point is this. What value is there in pointing to 15W40
undergoing oil analysis when no details are provided? We don't
know the make, model and HP of the engines that were tested
nor what the duty cycle was. As Jack Webb of Dragnet fame said
in every episode of his show..... " I want the facts Ma;am, just
the facts". LOL

If you have a particular thread on BITOG that you wish me to
read, then please provide the URL.. I am always open to new
information that might change my mind.
 
Josh, some folks are "Luddites" and are gonna buck change all the way.

I am that way with many aspects of life.

But synthetic oil isn't one of 'em.

It's the best thing that ever happened to air cooled engines.

While owner's/operator's manuals are a GREAT thing, looking at an old one written before some of these great, heat-resistant oils were available/commonly available is just a form of living in the past!

ONE example of how they resist heat is the difference between running dino oil and a good synthetic in OHV Briggs or Kawa engines that bend pushrods when a valve sticks.

In my limited exposure to small engines I have seen that happen many times, sometimes more than once to the same engine. I have NEVER seen it happen when syn oil has been used.

There's quite a few of the OHV Briggs around here on grain augers (that see seasonal use) and every one I've fixed I've told the owner's to run syn oil, with NO comebacks.

On the Onan side, I have 3 DEERE 318's that happily run synthetic, without leaking or guzzling.
 
All of the above is coming from a guy who readily admits to having LIMITED exposure to small engines.

First of all, if synthetic oils were absolutely needed in modern OHV small engines, then the manufacturers would insist on synthetic oil and void the warranty whenever regular oil was used.

Are we actually stupid enough to believe that pushrods get bent as a result of using Dino oil? That statement is such an insult to the members of this forum. Bob has absolutely zero proof that the pushrod bending problem was not caused by other factors such as incorrect valve lash settings

Lastly, this discussion has not been about modern OHV engines, Bob. Try reading the thread first so that you actually have an idea what the conversation is all about before you post. There is no need for me to comment further on your other misinformed statements other than to say that there are thousands of Onan powered Deere GT's that have been happily running on Dino oil since they first left the factory.

As for being a "Luddite", that too is an erroneous accusation. I don't reject new technology at all and if you had actually read the entire thread, you would have noted my positive comments regarding synthetic oils.
 
Sprint,
What you posted goes against what is said by the very people who make synthetic oil.

http://www.valvoline.com/faqs/motor-oil/full-synthetic-motor-oil/

http://www.royalpurple.com.au/index.php?ptl=articles_super_oil.php

http://www.castrol.com/castrol/genericarticle.do?categoryId=9014502&contentId=7017050


http://voices.yahoo.com/the-10-falsehoods-synthetic-oil-dispelled-5353667.html

http://habotmarketing.blogspot.ca/2012/11/can-changing-to-synthetic-engine-oil.html

https://www.opieoils.co.uk/pdfs/tech-articles/Oil-Myths.pdf

http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Switching_to_Synthetic_from_Conventional_Collection.aspx?pg=3


Can all these sources be wrong?

In the link below, Mazda tells people that they should follow Mazda's recommendations when choosing an oil for their rotary engines or......face the consequences. To me, this is a message that certainly applies to all discussions about oil choice.
Mazda
 
Imagine, companies dispelling a "myth" to sell product. I suppose smoking has no health consequences? If an engine did not leave the factory with synthetic, it is still a crap shoot on leaking and burning. I have seen it both ways, no problems and improved economy, and oil burning and leakage. Been in the auto business 20 years, not just making up personal experience.
 
Using straight 30W does not equate to using "old oils". The 30W of today is every bit as "modern" as any mineral based multi-grade oil out there. The discoveries about better refining methods are applied to all to all the oils sold by the manufacturers, not just the multi-grades.

Choosing to use 30W does not make you "old fashioned" either. The manufacturers of the engines know for a fact that their engines will consume multi-grade oils at a faster rate then if 30W is installed. Carbon buildup has the potential to damage the internal parts of an engine such as the piston, connecting rod and valves.

The less oil that is consumed, the less carbon will accumulate. It is as simple as that.
 
Tom your saying engine cosumes oil faster on multi-grade oil doesn't hold water. I have 4 garden tractor(2 powered by Briggs and 2 by Kohler) all have been run on Shell Rotella 15-40 T from first oil change. The oldest one is 27 years old and newest is 10 years old and not a one of them have been opened up and no carbon problems.The oldest tractor is a Ranch king with a 18 HP two cylinder Briggs with over 1,700 + hours. This tractor has no oil filter so oil on it has been changed every 15 hours.
I called Briggs when I got this Ranch King and told them that I wanted to use Shell Rotella 15-40 and was told they would honor warranty and that Rotella 15-40 was the only milti-grade oil they would let you use.
 
Mr. Beatty,
It is not ME that is saying that, it is the engine manufacturers themselves. Please paste the following URL into your browser and then scroll down to Section 1.4 and read the following paragraph on the left side of the page just about the diagrams of the dipsticks.

http://www.kohlerengines.com/onlinecatalog/pdf/tp_2379.pdf

Kohler states "Straight 30 - weight oil is preferred. SAE 10W30 and 10W40 are not recommended above 32 F or Zero C. Using these oils substantially increases oil consumption and combustion chamber deposits.

The Onan manual for the P-Series engine which is the most modern version they made, says the following on Page 6-1 of this manual.

http://www.wincogen.com/files/downloads/winco_engine_maintenance/onan_p224_service_manual.pdf


Use oils meeting the API classification SF, SF/CC or SG/CD. Refer to chart to determine the proper viscosity grade of oil to use. STRAIGHT WEIGHT OILS ARE RECOMMENDED for severe duty use and at temperatures above 32 degrees F for MINIMUM OIL CONSUMPTION.

Briggs and Stratton's website has a GENERIC page that speaks about oil choice. Keep in mind that there is no distinction between engines Briggs made back in the 50', 60's and 70's and the more modern OHV twins and singles they produced in the last 20 or so years. However, their chart does say the following under the 10W30 listing.

http://www.briggsandstratton.com/us/en/support/faqs/engine-oil-recommendations

10W30 is better for varying temperature conditions. This grade of oil improves cold weather starting but may increase oil consumption at 80 F or higher.

Obviously, the focus of the warnings is on multi-grades that begin with the number 10 as opposed to the heavier 15W40 you are using.

If you do not open up your engines, then it is unreasonable for you to state that you have no carbon buildup problems. Lots of people with Kohler K, Kohler M and Onan engines have made the tragic mistake of not removing the head/s at the recommended interval and ended up with a blown engine.

I also note that like so many others who have responded in this thread, you did not state the model number of the engines you have. The purpose of a thread is to stay on track and discuss the issue/s affecting a particular engine.

Does it make sense for you Doctor to start telling you about his experience with another patient suffering from lung disease when your problem has to do with your back?
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top