Synthetic diesel oil 5W-40 use in all riding mowers

GLMPA · Jan 31, 2020

Is it safe to use 5W-40 synthetic diesel oil in an air cooled or liquid cooled engine in a gas garden or lawn tractor. It seems to me this would provide the ultimate protection of the engine and be best with any external/environmental temperature for easy starting. Please comment. Thanks in advance.

MNGB · Jan 31, 2020

You asked this question 6 years ago on this forum

jeffcat · Jan 31, 2020

Ok so what was the answer??? Maybe he forgot. Guess you don't?

MNGB · Feb 1, 2020

https://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=gardent&th=120888

Texasmark1 · Feb 1, 2020

I use Rot. T6 in my newer tractors. I think I saw SN on the starbirst after the list of C ratings for the oil. I use wally world 1030 full syn in all my lawnmowers and it has proven to standup better whereby I can get by with annual oil changes and still the oil isn't all that dirty like was the case with dino oils.

Russ from MN · Feb 1, 2020

I was at a lubrication seminar once where a Mobil representative touched on this subject. He said synthetic was fine for running the engine in hot weather when used frequently, but when they sit over winter all the oil drains off the metal and it may rust and you will have a dry start-up. He said he switched to conventional oil in the fall, ran them a little and then put them away, switched back to synthetic in the spring, most of us would not go to that much bother!

ztrmowers · Feb 1, 2020

if that is what you think them do it and life goes on. me personally would not, I still use go old 10w30 and straight 30 in all small engines going thru shop, been no issues for over 14 years

tractorguy2 · Feb 1, 2020

I wouldn't without checking with the engine manufacturer first. I have several mowers. The old flat head Briggs get 15-40. The two Kohlers get 15-50 synthetic. and my new Toro states 10-30 full synthetic.

Texasmark1 · Feb 2, 2020

Finally, OEMs are including full syn to cover all ambient temp ranges.....took them long enough. Preferred listing seems to be 10w-30.

Sorta like CD ignitions. Forget the initials (J.C.???), but "Whitney Co." in Chicago had CD ignition kits for auto and truck aftermarket sales probably a decade before automakers decided to incorporate such.

Bob - MI · Feb 2, 2020

Synthetic oil acceptance varies by engine manufacturer.

Cub Cadet with Kohler 20hp twin called for 50 hrs run time on dyno oil before the switch to synthetic. John Deere X570 with Kawasaki twin doesn't say anything other than you should use JD brand 10w-30. New B&S powered 12kw generator says 5w-30 synthetic should always be used with the 1st oil/filter change at 5hrs. My Starcraft boat with a 4cyl GM engine in it says 40w straight weight in any weather warmer than 50 degrees even though the fill cap calls for 5w-30. Latest oils approved for that engine now include 15w-40 Mercury synthetic.

I have standardized on Mobil-1 extended range after reading their suggestions for air-cooled engines and I run that in all my small motors both at home and at the shop. A bit more expensive but never an issue. I also buy Wix filters from Napa so I feel I am doing the best I can when it comes to lubrication. Oil is a lot cheaper than engine repairs.

MSM · Feb 3, 2020

Use conventional oil for the break in period, then after that synthetic is fine. I do start my small engines over the winter and use stabil or seafoam to keep the carbs from gumming up. Never had a problem with synthetic

Synthetic diesel oil 5W-40 use in all riding mowers

GLMPA

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MNGB

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jeffcat

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MNGB

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Texasmark1

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Russ from MN

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ztrmowers

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tractorguy2

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Texasmark1

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Bob - MI

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MSM

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