or every 3 months (whichever comes first), then it really doesn't matter. I've been using non-synthetic oil since 1995 when I bought my TT brand spanking new. She now has 82,000 miles and Z mechanics and other "prominent" members of TT.net I've talked to recommend to continue using non-synthetic oil. Get the Nissan OEM 60U filter and Mobile/Pennzoil/Castrol oil and change every 3000mi/3mos.