Mobil 1 15W50 UOA

[Apex Hunter]

M1 15w50 does not hold up as well as I had hoped. It sheared down to something more like a 5w20 after one track day and 1 dyno tuning session, along with fairly conservative street miles. For what it's worth we started from scratch on that tune, so lots of pulls at varying ramp rates.


I'm going to send in another sample shortly with last Saturday's track day at CVR, and only about 400 Street miles to see what it looks like. That will determine if I can continue using this oil, or if I finally need to start using RL 15w50 that i know will be more shear stable, but at almost triple the cost. I've been getting Mobil 1 15 w50 from Walmart for <$5/qt.

[jbenosa]

What's your thoughts on Brad Penn 20W-50? I buy a case of 12 qts for $60 at Roy miller Freight Lines in Anaheim.

[Apex Hunter]

I know a lot of people swear by it, and it has a shit ton of zinc and phosphorous. The concern for me is that last i checked it is a semi-synthetic in the Group III class, so it uses some conventional base stock. Group IV and Group V oils are purely PAO or Ester base stocks, making them the real deal Full Synthetics. Above 240*, the oxidization rate of conventional oil skyrockets, and this is where the synthetics really shine. At the track i'm thrashing the oil for 20+ minutes at >240*F most of the time.

The non-racing formulas of Mobil 1 are all Group III these days. In USA, an oil only needs to be made up of 30% synthetic base stocks for a manufacturer to call it "Full Synthetic". So if i switched to the Brad Penn 20w50 that everyone loves, i suspect i will be in the same boat i am now. Maybe their Full Synthetic line is Group IV or V? I would like to get my hands on some UOAs, and see how their Semi Syn and Full Syn hold us to track day use, because it is clear that they can make a great product.

[jbenosa]

Oh i see, thanks for sharing your input!

[Apex Hunter]

M1 15w50 gets a pass...for at least one track day and some street driving anyway.


Last UOA had the M1 15w50 looking more like a 0w20 after 3k miles, one track day, and a strenuous dyno tuning session.

I was about ready to write off this oil and begin looking at better alternatives, albeit with a price tag 2.5x times higher. Before doing so, i wanted to do another UOA, this time the only use being driving to the track, at the track, and back home.


I was pleased to see that it held up just fine. Good thing, because i've still got another 10 qts of this stuff on the shelf, and i'm happy to continue paying $5/qt for decent performance and detergent/zinc/phos levels.