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Signman · 04-13-2013, 08:08 AM

Was interested in this topic a while back and found a study on Speed Talk a racer / engineer did. His findings were based on testing about 60 off the shelf and racing oils in a machine that tests the compressive strength of each. If I remember correctly Mobil 1 5/30 was one of the top 5 oils on the list.

The discussion was on break in of flat tappet engines and the actual function of the break in procedure as it being allowing some wear or not. The novice would think that the practice would endeavor to protect surfaces from wear but actually it is about allowing some. The tests showed that break in oils actually had lower compressive strengths therefore allowing wear but had higher zinc to protect from failure.

The most interesting piece of information for myself was that actually zinc is added to protect the metal to metal contact area after the compressive strength of oil has been exceeded.

Another point of view would have argument for this and has but the interesting point to me was that the addition of zinc is actually a last ditch effort to save the parts after oil has failed.

Many flat tappet and roller engines seem to have oil related failures.
Many have none without using high zinc oil. Engine builders without failures in their racing engines consistently freshen to freshen attribute it to geometry and machining tolerance.

The shop that helps me out (Simonek Performance) has a relationship with Jesel. They worked with an endurance team running GM LS engines. New engines were installed and run. Engines were torn down after the race: Roller lifters were found to be heavily worn and near catastrophic failure. Jesel did research and testing with finding the "metal finish" was incorrect. Parts were processed and installed, after the next race inspection found parts were in great condition.

With this it seems that the compressive strength of oils is being exceeded causing metal to metal contact.
It has been known for a long time that adding zinc covers over much of the oil related failure.
But it appears that the cause of oil failure and therefore the need for zinc is machining tolerance, geometry and metal surface finish.

Really interesting stuff!

04-13-2013, 08:08 AM	#7
Signman Senior Member Join Date: Oct 2003 Location: Lower Slower Delaware Posts: 535 Likes: 22 Liked 269 Times in 99 Posts	Re: Oil additive? Was interested in this topic a while back and found a study on Speed Talk a racer / engineer did. His findings were based on testing about 60 off the shelf and racing oils in a machine that tests the compressive strength of each. If I remember correctly Mobil 1 5/30 was one of the top 5 oils on the list. The discussion was on break in of flat tappet engines and the actual function of the break in procedure as it being allowing some wear or not. The novice would think that the practice would endeavor to protect surfaces from wear but actually it is about allowing some. The tests showed that break in oils actually had lower compressive strengths therefore allowing wear but had higher zinc to protect from failure. The most interesting piece of information for myself was that actually zinc is added to protect the metal to metal contact area after the compressive strength of oil has been exceeded. Another point of view would have argument for this and has but the interesting point to me was that the addition of zinc is actually a last ditch effort to save the parts after oil has failed. Many flat tappet and roller engines seem to have oil related failures. Many have none without using high zinc oil. Engine builders without failures in their racing engines consistently freshen to freshen attribute it to geometry and machining tolerance. The shop that helps me out (Simonek Performance) has a relationship with Jesel. They worked with an endurance team running GM LS engines. New engines were installed and run. Engines were torn down after the race: Roller lifters were found to be heavily worn and near catastrophic failure. Jesel did research and testing with finding the "metal finish" was incorrect. Parts were processed and installed, after the next race inspection found parts were in great condition. With this it seems that the compressive strength of oils is being exceeded causing metal to metal contact. It has been known for a long time that adding zinc covers over much of the oil related failure. But it appears that the cause of oil failure and therefore the need for zinc is machining tolerance, geometry and metal surface finish. Really interesting stuff! __________________ Frank Ferrucci I/SA 1271 "Be Thankful for the Gifts You are Given"