My car has 230k km on it. Bought it not too long ago, so I don't know if the gear oil has ever been changed. Should I change it to Redline or should I simply leave it in?

Other question: The other day I put some 10W30 synthetic Mobil1 in my car. Winter's approaching pretty fast. Should I change it to 5w30 or 0w30 now? I'm already getting sub-zero temps. Nothing beyond -10 but still, should I change it right away instead of waiting until the next scheduled maintenance?

Thanks

There has been posts reporting tranny started slipping after a very ATF change. This is caused by the small debris and metal shavings floating in the fluid which increases friction between bands. Remove them, friction is reduced, slipping might appear. If the ATF has never been changed, the wear and damage is there.

Not sure what to recommend, other than if you do change the ATF, keep the old ATF for a little while in case it slips to much: you can put some old ATF back in.

My car is a 5-speed though... I'm guessing ATF means Auto trans fluid.

Oh1 I hadn't realized you had a stick. Different story. Yes you may change the gear oil anytime. Clean oil should improve shifting. Go ahead and do it.

As far as engine oil is concerned, 10W30 is oK for as low as -20 C. If your battery is weak, of course 5W30 or 0W30 will help crank the engine. Up to you.

You're better off with the lower weight oils in your case. Mobil 1 10W-30 will still flow at very cold temps, but the 5W-30 or 0W-30 are much better.

I changed my ATF for the first time since the car was purchased new in '92, at 136k miles..noticed no slipping, and compared the fluid I was using to flush out any old fluid with the actual old fluid..a somwhat dark red (from the small ammounts of older fluid mixed with it) compared to BLACK fluid that came out of it in the first place..I didn't do anything to the screen, just a flush and fill ('92 GXE btw, so theres not really a "pan" to drop, wipe out, and put back on, and the screen is harder to get to) I used cheap fluid, since I'm going to do a 5 spd conversion as soon as I get the money for all the parts and rebuild the donor tranny..shifting smoothed out a lot, and its a tremendous peace of mind knowing my tranny isn't being sandblasted by as many metal shavings..