I am confuse.
NOS booster contains MMT and the manual recommend not to use it. Otherwise it may not be covered by Subaru warranty.
I am missing something?
I went to two autoparts stores (R&S Strauss & Pepboys). Most of the octane booster contains MMT. I get all the octane booster brand that doesn't mention MMT on its label. However, how I can be sure that these products effectively does not contain MMT.
Any additional input is greatly appreciated.
Originally Posted by blinguskahn
+1. Absolutely the best idea is to just add octane to the tank if your super is 91. If your location was entered in your profile I would be albe to avoid the IF and tell you IF your super is 93 then 1/2 93 and 87 will be safe and you dont have to worry about it.
If your super is 91 than I would worry about it. Yes you can stay out of boost till your are empty and refill but even with straight 91 the 2.5L engine is known to knock. If I were you I would put some race gas or NOS octane bbooster in there RIGHT now. For a full tank go with at least 2 bottles of NOS booster if using race gas do 1 gallon now and when it drains another gallon driving around put 1 more in.
For a good site to calculate your octane mix go to: