Oil weight on a rebuilt engine for a Ford 4500 TLB

Ray T. · Dec 10, 2015

Hi Folks,

I just had my 3 cylinder 201 cid diesel engine rebuilt for my 1971 Ford 4500 TLB. I had been using Rotella 15w - 40 oil which I thought would be fine for a 45 year old diesel engine.

Now that the engine has been completely rebuilt I see that the Ford owners manual recommends SAE 20 for temps between 32 - 90 degrees. Does anyone have any suggestions, thoughts or recommendations on using a 20 weight oil on a newly rebuilt engine?

Thanks,
Ray

gears · Dec 10, 2015

Personally I break in my motors with a cheap Diesel grade oil and change it after an hour's run time. All the Diesel oil around here is 15w40.... If I could find straight 30 T3 SJ rated oil I'd use that.

Dean · Dec 10, 2015

20W diesel spec oil (or lighter if you can find any) will be fine for initial start up. You want the rotating assembly to throw lots of oil upon start up of a newly rebuilt engine.

If the engine was assembled with molybdenum disulfide assembly lube, change the oil and filter after the first hour or so.

15W40 diesel spec oil will be fine thereafter.

Dean

RickB · Dec 10, 2015

I have become a convert to 10W-30 for these engines when fresh unless they will be run hard at ambient temps above 80* F or so. Low oil pump volume is a non-issue when all is right.

M-MAN · Dec 11, 2015

I would use a good 20 or 30wt Non detergent oil for the break in and then put the Rotella you've been using back in. Deere still has break in oil(non detergent) on the shelf. Don't know about NH.

sotxbill · Dec 11, 2015

That manual was printed BEFORE modern HD oils existed. so in cold weather, yes 20w was to be used. However... Now you can get a 15w40 the performs even better as a 15w in extreme cold starting conditions yet when hot is does NOT thin so it performs like a 40 at 220 degrees. It CLEARLY passed the performance of 20w oil.

My question is... WHY would you want a lower performing oil???

If you run in extreme cold conditions and do starts below zero... then get even a better oil and run 5w40 oil.. It does well for snow removal equipment.

Some modern Light duty engines are going to an HD 20w oil... not to last longer, but to allow a tiny bit more mpg. Since engines are now lasting well over 100,000 miles, they no longer care about wear, but are trying to meet (cafe)federal demands for higher gas mileage under light loads.

Oil weight on a rebuilt engine for a Ford 4500 TLB

Ray T.

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gears

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Dean

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RickB

Well-known Member

M-MAN

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sotxbill

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