Mobil 1 - Q/A Flat Tappet Cams

[buster]

Question:
Does Mobil 1 Contain the Additive for Flat Tappet Cams?
I build a few engines a year as I do muscle car repairs and I have been having a lot of camshaft failures. I just read that it is because the oil no longer has the additive for flat tappet cams. Can I use Mobil 1 to break in fresh rebuilt engines of '60s and '70s tech? Is it too slippery for new ring break-in? Will it give protection on new cam and lifters?
-- Frederick Neidlinger, Dover/Dover AFB, DE
Answer:
For older, flat tappet engines where wear may be more of a concern, we offer a number of oil products which are higher in phosphorus than API SM/ILSAC GF-4 oils. These include Mobil 1 15W-50, Mobil 1 Extended Performance 15W-50 (1200 ppm phosphorus), Mobil 1 0W-40 (1,000 ppm) and Mobil 1 High Mileage 10w30 and 10W-40 (1000 ppm). For all newer engines and flat tappet engines in normal service, API SM/ISLAC GF-4 oils are preferred for better fuel economy and for the protection of catalytic systems with lower phosphorous (800 ppm).



Amsoil has a good TSB on this subject and they "seem" to suggest that the new additive chemistry is absolutely fine for older flat tappet cams. It's not cut and dry from many of the engine builders though. Throwing in poor manufacturing throws a curve ball into the equation.

 

[wileyE]

There's also a big difference between a stock flat tappet engine that has been in service for years, and a new hi perf build. The stock cams ramps are mild and spring pressure low, the lifters and cam faces have been polished together from years of running and heat cycling. The older stock cams with some exceptions seem to be lot harder than some of the new aftermarket stuff. So when hot rod magazine, or the like, has trouble with flat tappets, it doesn't necessarily apply to all flat tappet engines. That's the distinction that always seems to be left out. An older engine, IMO, can run the new oils without worry IMO.

 

[aldead]

Mobil 1 is fine fro breaking in freshly rebuilt/remanfactured engines. If you want to use Conventional oil, use Shell Rotella, Chevron Delo or another high grade diesel engine oil. 15w40 in a hi-ouput engine will work great. Make sure that the oil has certifications from API with Sl or SM designation. S series designation means that the oil has all of the right stuff for gasoline engines. Primary additive missing for flat tappet cams is Zinc, diesel engine oils still contain levels of Zinc.

 

[wgtoys]

It seems that Mobil's answer was actually a very good one. It also indirectly explains some of the thought behind the new Mobil 1 High Mileage formulations.