Mixing oils?

Hello can I mix oils?

__________________
This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: BMW Oil Change

[Wayne 962]

I typically recommend against mixing oils. If you're topping up with some oil, then I would top up with whatever's in the engine currently. However, this is not always possible, and the reality is that it will probably not do you any harm.

- Wayne

[bostogrun]

Oil schmoil!!!!

I had a 525i for three years. I changed oil every 3k with the cheapest stuff I could find at Walmart usually $9.00 or less a gallon. Guess what 75,000 miles and no problems or increase in consumption. All oils are made to such high standards now that the differences between synthetics and dyno oils are disappearing. In my opinion, its better to use more affordable oil but change it more often. I guarantee that if you change oil every 3K you will never have a sludging or oil seperator probelm .

[Pilgrim]

Most oil chemistry isn't that different unless you're jumping between standard petroleum oils and synthetic oils. I do not recommend adding standard to synthetic or vice versa. Again, even if you do this the chemistry of the oils is unlikely to be different enough to cause any problem.

Editorial comment: When you're running a BMW, there is no reason to go against the manufacturer's recommendations and run cheap oil. Although standard oils are excellent, synthetics are superior and allow extended change intervals.

[bostogrun]

I agree with the last post. I just think this oil issue is over blown.
Most of the people who are on the oil bandwagon don't have any idea of the chemistry involved with oil.

[JhwShark]

On old cars stick with classic dino oil used before the synth's...synth's ocupy less space such that when you put synth's in a car that had classic the gaskets eventually absorb the synth and then can cause leaks...they don't swell as much