S2TGART

I rechecked the owner's manual and 20W-50 is good for temps down to 15 deg f. 15W-40 is good for temps down to 5 deg. So 15W-40 will be good for the coldest days of winter here in CT. In the spring, I'll put in 20W-50. 15W-40 covers the same temp range as 20W-50, plus the 10 degrees lower on the cold end.

hanzonn

All,

Thanks for the recommendations. I had a significant "*****" when shifting into 3rd gear. I sent an email to Redline and they answered back that it sounded that my oil was too *slippery* for the synchos, and didn't allow them to match up properly. I drained the tranny oil to find that is seemed almost new - nice & clear, no shavings on the magnetic drain plug. I thought - "what good would new synthetic oil do?" I changed anyway to Mobil 1 and now the tranny shifts much smoother. I think Redline would have been just as good; I just couldn't get it anywhere close to my home.

Greg

der Mond

I run Mobil1 0W-40 in winter due to starting at 0 degrees or colder (I try to not use the car if below -10 F.) I also take it easy on the revs since it tends to not get up to ideal operating temps in winter. I can't prove it (yet) but I'm banking that the 0W synthetic oil still pretty much prevents metal-to-metal contact as the thicker stuff does in summer. I've had phenomenal success w/ Mobil1 0W-30 and 0W-40 in a Honda Civic Si (282K miles) and a Cherokee and Dakota after 6 Alaska winters. The synthetic stuff does leak more, particularly the 0W stuff. After buying the car at 19K miles and switching it from Castrol to Mobil1 it did have more leakage, particularly the upper internal oil thermostat O-ring seal, which I replaced by doing a Houdini-Watusi-like maneuver. The flexible oil lines are next, which
I will have a dealer replace since I can't get them to budge from the forward thermostat even after soaking in PB and heating to cherry red. Good Luck! Oil is like religion, most owners and mechanics swear by their opinions. Best to read a great deal of opinions.
Dennis

der Mond

BTW, I replaced my G50 tranny oil w/ Redline NS 75W-90 at Redline's suggestion: I mail-ordered the stuff (sorry, I'm a OCD German). The Redline tech guy said that 911's tend not to chatter. Mine did, so I added GM friction additive and it works fine.

der Mond

I just wish I could magic-wand-away my G50 rattle, but it seems to not get worse.