15w-40
- Thread starter 1929
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Jim Brierley
Well-known member
Rotella is made for diesel engines and has additives that may be less than ideal for gas engines. I use 15-40 but not those specified for diesels.
All the 15W-40 containers I saw, all have heavy duty diesel, I couldn't find anything different.
Patrick L.
Well-known member
Who are those break-in instructions from ?
15-40 oil that I'm familiar with is diesel oil. There are several different brands and all should be compatible for gasoline engines. Newer gas engine oils have very little zinc which was needed on older flat tappet engines. So, some fellas like diesel oil in their A's due to the extra zinc.
15-40 oil that I'm familiar with is diesel oil. There are several different brands and all should be compatible for gasoline engines. Newer gas engine oils have very little zinc which was needed on older flat tappet engines. So, some fellas like diesel oil in their A's due to the extra zinc.
Seth Swoboda
Well-known member
Patrick has it correct. 15-40 Shell Rotella is perfectly acceptable to run in your Model A and any other flathead engine you may have. It does have a zinc additive that is very friendly to your Model A engine.
I was given a bottle of ZDDPlus, the rebuilder said to add to the oil because it restores the zinc and phosphorus levels in the oil and is needed for flat tappet cam engines.
1929, read an article written by Lake Speed's son. He is the oil Doctor for Hendrick's Motors in NASCAR. He claims engines should be broken in with NON detergent oil. His reasoning is detergents and zinc "compete" to attach to new engine parts, like bearings. After the zinc attaches itself during break in then switch. He explains it in very clear terms, article should be able to be found online. I read it in a engine rebuilder trade magazine.
Mitch//pa
BANNED
Do what your rebuilder says even though it's not needed
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Mike V. Florida
Well-known member
Do what the instructions say if you want a warranty honored! Keep the oil receipts as proof you did what you were told.
Best of luck with the modern seal.
Best of luck with the modern seal.
Chuck Sea/Tac
Well-known member
Might be the same article in this months Sacromento vintage news letter. The importance of zddp by lake speed jr of driven oil. He does work for Gibbs racing.
agree, the rebuilder has over 30 years experience with zero complaints and an excellent reputation.
Mitch//pa
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C26Pinelake
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I totally agree with Mike in all aspects ! Wayne
FYI: Zinc levels in Rotella T have been reduced below the ~1200 ppm level that's supposed to keep flat-tappet cams alive. SOMEWHERE I've saved a web page that shows the zddp levels of most major brands of oil. Believe it or not, the Traveller brand from Tractor Supply tested as one of the best.
You are correct, he works for Gibbs.
Instructions are as follows: engine break-in for engines with a modern rear seal, engine oil must be added to your newly rebuilt engine. The Model A has a 5 quart capacity. To begin the break-in of the engine, put 4 quarts of SAE 15W-40 detergent oil in the crankcase. Add a fifth quart through the distributor hole in the head. This allows the mains to have oil before the oil pump can feed the mains. Along with the new oil, you should add a bottle of ZDDplus. This restores the zinc and phosphorus levels in the oil, which have been reduced for emission purposes. However, testing has shown that these additives are needed for flat tappet cam engines. without them, premature camshaft and tappet wear may occur.