Mobil Ep vs Reg Mobil 1

[Meat]

Sorry guys if this has been asked before.

I noticed on the Mobil EP bottle that it doesn't have the "Meets Gm Specs". First, could someone tell me why?
Second, is this EP really any better than the reg Mobil 1 ?

Just trying to find a good oil for my 05 corvette, and answer some questions from some other corvette owners.
Thanks for your help

 

[Triple_Se7en]

Your warranty asks for shorter OC intervals than the 15K offerings of EP. Your engine and wallet would be better-served by sticking to the regular Mobil-1, Castrol GC or Pennzoil Platinum.... should they meet the Corvette ratings demands.

 

[adam123]

I agreed to that the Ep leaves more room for some Abuse. So I chose the Mobil 1 EP for my 05 Dodge Ram.

 

[KJA426]

The EP is SL rated which means it contains the old level of zinc and phosphorous. This MAY result in better camshaft protection as opposed to using the new SM formulation.

 

[SSDude]

Doesn't GM now say that the oil should be changed every 15,000 miles in the Corvette?

 

[Blue99]

Two of the GM specification stumbling blocks, for M1 EP motor oil, are the GF-4/SM 800 ppm max limit on ZDDP (Phosphorus) and the 1-2% GF-4 fuel economy performance ratings.

No direct link has been established, that indicates phosphorus levels of 1000 ppm ZDDP, will poison a cat within the 150K mile auto manufacturer's warranty period.

Phosphorus does volatize from the ZDDP, but the level seems to be dependent on many factors such as overall quality of the motor oil, engine characteristics, driving style, climate, etc.

Bottom line is that while M1 EP does not carry certain specifications, it certainly meets or exceeds all these specs on a performance level.

I'd certainly select EP over the standard M1 for any synthetic oil application.

 

[ScottB]

^^^ Even for us 3k mile OCI-ers?

Scott

 

[GMorg]

My understanding is that the zinc level is too high in the EP line. Catalytic converter poisoning/regulatory issue.

 

[Dick in Falls Church]

From the specs I've seen the EP is a better formulation.
It would be my choice, were I to choose Mobil 1.