This weekend, cleaning out my car's trunk, I found a neat leather organizer that apparently came with the car -- at least, it had the MB star embossed on it. (Yes, I've had this car 18 months; you ask why I never found this before? I answer, I dunno.) In it was the Factory Approved Service Products brochure that I'd expected to find in the glove box, or written in the owner's manual. Now bear in mind that this is from 1997 or so, when the highest API oil grades were SG and SH. Anyway, the chart indicates that the SH 10W-30 is good to go from about -10 F. to about + 90 F. (but no higher). This is a considerable improvement over the SG grade of 10W-30, which is only approved for -10 F. to + 50 F. So my question: At present I have SL grade 10W-30 (TropArtic synblend, if it matters) in the car's 4-cylinder, normally-aspirated engine. NO is currently going through its blink-and-you'll-miss-it winter, and we should start seeing temps in the '70s soon -- though probably not the 90-degree range until May, when I plan to change to 15W-40 again. Now given the enormous jump 10W-30 showed in capability between SG and SH, is it fair to assume that with SL grade, my engine should be okay even if we get some low 90s in the next 3 months? -- Paul W.