Well, I've posted about this before. My 94 Corolla that I recently bought burns oil like a mad man. On the highway, it's about 1 quart/1500-2000 miles I'd say, but it seems to be worse in town. I recently filled up with 5w-30 Pennzoil high mileage, and it's burnt darn near 1/2 quart in 400 miles I've done Auto RX, didn't help consumption at all. I thought this car was well taken car of (1 owner with ALL the records), but I think the other owner was a bit lax on oil change frequency. It doesn't smoke at all. Doesn't leak or drop any. Where is the oil going? Past the rings? I guess it's on to 40 weight next to see if that improves things, but I'm limited to 5w-40 because of winter conditions. Don't want to run regular 10w-40 because of the noted thinning, and 10w-40 high mileage would be too thick for cold temps IMO. So, 5w-40 Rotella it is because of price mainly and it is a solid oil. BUT, I'm still worried about the whole diesel oil in a gas engine thing Even if it slows consumption a bit, it will still be passing a lot of phosphorus though the cat. Also, on the Rotella.com forum, the "Tech expert" indicated that if your car calls for any of the GF standards in the manual, to not use it for fear of catalyst poisoning. He says to only use it in a gas engine if your manual only calls for an API oil designation such as SH/SL etc. What do ya'll think? Has anyone out there successfully run one of the mixed fleet oils for a LONG time in an oil consuming gas engine?