Up front, I'm thinking of dropping this stuff in my other ride. It's a "commuter" with a four banger and rarely gets any heavy foot action, so no "high performance" concerns.

Just inherited a case of Mobil-1 15-W-50. The 4-banger in the commuter ride calls for 10-W-40. If I remember the way those numbers work, that means that the 15-W-50 is the "thicker" of the two. That right?

If that's so, I'm thinking that it would be best to wait until a springtime oil change to drop it in, rather than running a "thicker" oil than the engine calls for in the winter, cold starts and longer to warm up and all that...

Don't want to let a case of the "good stuff" go to waste. Anybody see a problem with using this stuff next summer? (I was thinking of going 3K with it, then change the filter and shoot for another 3K after that.)