Quote:
Originally Posted by shiro
I've decided to use Mobil1 5W-30 for my new build. Reason, because in my area Mobil1 is more convenient to find and I would have to special order Motul. Plus, I've found a lot of places to price match Walmart's price. I get 5qts for about $24.99 (vs $37.99 at the auto parts stores) allowing for more frequent oil changes. 
As for E-85's effects on Mobil1, I have not heard anything negative, but I personally do not have supporting facts, yet. I will have to see what the oil looks like when I do my next oil change.
After a long repair process, Full Blown is Dynoing my car today (19 Mar) and then I need to dump the oil since we just got past the engine break in phase. Maybe I can take some pictures of what the engine break-in oil looks like. I'll put in the same oil (Mobil1 5W-30) run it 3K-5K miles and hopefully get back. My first 400miles on this oil change with 91 octane & E-85 mixed (flex fuel kit :]) will be this weekend.
Overall, you can't go wrong with the higher end oil (hopefully with higher zinc).
(side note) I personally wanted to try Shell Rotella T6 oil (heavy duty engine oil) because of the high amounts of zinc and support for turbo'd engines. I've seen a few WRXs and Audis running this oil. However, I haven't seen it used with high octane fuel like E85 so that would be interesting.
Best of luck in your oil search
Edit:
By the way, I would be really interested in your results on this oil. I've heard really good results from Shell's T6 oil on boosted cars (but not much on E85 yet). |
Mobil1's web site actually recommends M1 TDT 5W-40 for E85 applications, although I would
never go this thick in a BRZ/FR-S on stock internals. I would be tempted to boost M1 0W-20 with Mobil1 Race 0W-30 or a little M1 0W-40 for the added detergency.
When M1 reformulated to API SN, many of their passenger car oil now have a similar detergent package as the diesel oils (lower calcium and higher magnesium). Check the VOA forum at bobistheoilguy.
-Dennis