Quote:

Compsyn, I am familiar with the diesel oil, but haven't looked at the racing oil.

Several years ago, when this whole SM oil controversy was just starting, I built a new engine for the TT340. I broke it in on Rotella, and then, at the recommendation of Amsoil, switched it to 5-30 diesel oil. It had run 500 miles on the Rotella without issue, and then failed 3 pushrods within 200 miles on the Amsoil. I replaced the pushrods and rockers and broke them in with Rotella again, then went to 15-40 Amsoil diesel oil, at their recommendation. The pushrods failed again within 300 miles. At that time, Amsoil would not tell me how much additive was in the oil, and they would not answer my question as to if they were using their same SM oil with soot additives. This was also during the period that they claimed older cars and small engines would be just fine on their SM oil. Their story has now changed on that. The pushrods and rockers were again replaced, broken in with Rotella, and then switched to Mobile 1 motorcycle oil and there have been no more issues. I guess I just don't trust Amsoil products anymore, justified, I don't know. I also don't know if the racing oil has reduced detergents, as many racing oils do.

The other issue is that I don't run synthetic oil in the daily drivers, so those would be of the question for me, anyway, on most of my vehicles.

I am glad that folks are finally starting to admit that the SM oils are a potential issue, and coming out with better oil packages, but there are weaknesses in most of them.

Diesel oils-many are now reduced additive and some of the additives are not the best for gas engines. There is little/no choice in low visocity non-synthetics.

Old car oil has good oil, but usually carries a solvent to swell seals, which is not for an engine in good condtion.

Motorcycle oils are great, but viscosity selection is limited.

As I said, using additive is not my first choice, but I think the choices I would like don't exist yet.

What I use:

TT340 1970 Chally-10-40 or 20-50 Mobil 1 motorcycle oil.

John Deere lawn tractor-air cooled-the same Mobil 1 10-40 or Brad Penn 10-30

Drivers-old Escort (200+k), Old Tracer (125+k), new Chev 6.0 campervan, new Honda crv--Castrol 5-30 SM oil with 1/2 bottle of EOS.

The only oil related (assumed) failures I have ever had in 40 years were the above mentioned pushrods on Amsoil.



booster,

Sorry to hear about the run of bad luck with your 340. By chance, did you file a warranty claim with Amsoil at the time? I have seen a few reports of people experiencing "assumed" oil issues with Amsoil. But they said Amsoil was upfront with them and prepared to resolve the issue. I’d be disappointed if this was not the case.

Just for curiosity, what was the timeframe that this happened? Amsoil published this Flat Tappet and Camshaft Lobe Lubrication Technical Service Bulletin back in 2007. I do recall that the oil industry as a whole claimed that the newer API (SM) rated oils were compatible with flat-tappet cams when the SM category was first introduced in 2004.

Interestingly, according to this Hot Rod Magazine technical article, Flat Tappet Cam Tech - Righting the Wrongs, the author asserts that the camshafts used in the early SM oil testing had better surface hardening than typical camshafts stating,

“Motor oil industry sources maintain that even with their significantly reduced anti-wear additive content, the new oils still pass standard industry tests that measure valve-train wear (including with flat tappets). But cam grinders counter that the type of heat-treat used on the reference test cams was atypical of standard industry practice. Who’s right on this one is hard to determine.” - Hot Rod Magazine

Quite possibly, Amsoil bought into this fallacy as did the rest of the oil industry at that time and assumed that their SM rated oils were compatible with flat-tappet camshafts, and we all know the end result. This makes since that people gave up on the industry and began mixing in their own additives of choice; still very much a popular practice. But today, we can see that Amsoil as well as others have addressed the issue of zinc/phos levels and flat-tappet cam use. And with the wide range of oil analysis labs available to the public, we have the ability to periodically test the oils we put in to our muscle cars to make sure no secret re-formulations have occurred. For the most part, I think the oil industry as a whole is much more forthright with regards to this topic than they were in years past. Plus with the other resources we have in oil analysis and the Internet, we shouldn’t have to be in the dark any longer.

Lastly, to your question about detergents. The new AMSOIL Dominator® Synthetic Racing Oils have been shown by Virgin Oil Analysis (VOA) to have reasonable detergent amounts for street use with a TBN of 6.4. So this oil is actually a good multi purpose street/race oil that would do well in a 3,000-5,000-mile street driven oil change interval depending on the application.

CompSyn