Is it bad to mix new oil with old oil?

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Feb 22, 2004
Eastern Seaboard
I don't know jack about oil, but it might be good to know what "pretty low" is. Are you 1/2 quart low?
2 quarts low?
4 quarts low?

Originally posted by Al:
The closer you keep your oil to the full line the dipstick the better-period.

And some of us even like to go slightly higher than the full line too, maybe 1/4 to a 1/2 quart over, in some cases.

In the LS1 engine, it's completely safe to go 1.5 quarts overfilled, in fact it's even mentioned in a GM videotape given to Corvette owners that they should do this when roadracing or autocrossing, to prevent oil starvation.
I put in some M1 0-40 about 4k miles ago and my i checked the level on it yesterday and its pretty low. I am going to dyno my car tomorrow. My question is, is it bad to put in a quart of new M1 0-40 oil or should i leave it at the level that it is now? I just dont have time to change my oil today so I want to know what i should do.
Topping up is a normal practice. I don't see any problem with adding, but if it burned off that much, maybe you need a thicker oil in the future. Is what remains in the crankcase pretty nasty? If so, I'd want to get it out. Otherwise, top up, but if you are changing it next week, I would use low priced oil, whatever is on sale today, but in spec (SL, not SA).

[ February 27, 2004, 12:30 PM: Message edited by: TallPaul ]
I have a turbo car with about 70hp over stock and I drive it pretty hard most of the time, so i think the oil consumption is pretty normal for the conditions. The oil is a bit dirty but not too bad.
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