Mixing Oils W/ Diff't Weights

[EarthQuake]

I need to add some oil to my wife's car and it's recommending 5w-30, I don't have any of that on hand so is it going to cause a problem if I add 10w-30 to the 5w-30 that's already in there? I plan on having the oil changed this week anyway, but just wanted to be on the safe side.



Thanks!

 

[Randy]

No problem, won't hurt a thing...

R

 

[02-Z66]

i would not worry much about that. just never mix traditional, synthetic blend, or full synthetic. other than that you should be okay.

 

[EarthQuake]

Will do.
Thanks guys!

 

[RJLACK]

As long as your going to change it soon I think you are fine. Option of waiting till oil change is one way - I am sure it makes you uncomfortable to run a quart low but it will be fine a day or 2 - as a rule stick with the same weight oil and certainly stick with the type, I like to also stay with the same brand - but thats just me.

 

[Big_Don]

I always thought the "stick with the same brand of oil" was an "old wives tale" or perhaps "old mechanics tale", but it appears that there may be something to it. I was attending a seminar given by Pat Goss, the mechanic on the MotorWeek TV show, and he said that every oil manufacturer adds chemicals that cause the seals to swell in your engine and help prevent oil leaks. Since each manufacturer uses different additives to do this, switching oil brands frequently may lead to oil leaks, since the seals will react differently to the different additives. At least this explanation makes sense.

 

[openminds]

I used 2 quarts of tranny fluid in my oil once to get home...... Took it into oil change shop and guy told me it was the best thing to do, tranny oil has detergent in it. Who knew? Recommended I run a quart in my oil for the last 500 miles or so b4 an oil change to help keep everything clean.

 

[Big_Don]

I wouldn't reccomend using transmission fluid in your oil crankcase under any circumstances. There is plenty of detergent in any quality motor oil that you buy. If you want to "clean" your engine, buy some oil when it is on sale, cahnge your oil, run it for 500 miles and change it again. I don't thnk this is neccesary if you follow a reasonable oil change interval, but it is a safe way to clean the inside of your engine if you feel it is needed. It is funny how we listen to the mechanic and take his advice when it contradicts what the engineers that design our engines tell us. Changing oil, or parts for that matter, does not make you an expert in mechanical engineering, petroleum formulations, etc.. For the most part, just read and follow the directions in your owner's manual. That is written by people that know much more about oils, cars, and service intervals than "Joe down at the corner gas station".

 

[colek]

While I wouldn't recommend using transmission fluid at the last 500 miles of every oil change, I'd certainly recommend it over any of the additives like Pyrol Engine Flush which is almost straight kerosene. If you've gone an excessive amount of miles between your last oil change you can safely add a quart of transmission fluid to help clean up some of the sludge that has built up provided that you only do it for a few days and don't drive very hard during those days. I don't think you'll find an engineer who would say different... Allright, where's 11H ?