People question whether the base stocks or additive packages of different oils are miscible. It's not a dumb question, even if the answer is yes and has been said hundreds of times. The dumb part of this is not the question itself, but not using the search button.
There are only a hand full of additive producers and an handful of oil producers and the oils are designed to be compatible. I would say why don't you buy add oil when buying the oil to do the oil change saving a trip to the store.
That isn't the deciding factor. Any oil which passes ASTM D6922 has proven that it is miscible with any other oil that also passes the test. This test is part of all API licensed oils so if that's what you're mixing then you have assurance that there will be no resulting harm from the mixture.
I've often read that when repacking wheel bearings you should remove all the old unknown grease from the hub so you don't mix that with the new grease. Not sure why but grease is basically thick oil so why wouldn't it apply to oil as well?
Grease incompatibility is far more a "thing" than for an API licensed oil.
I looked back through this thread, who thinks it's a bad idea?On one hand you have the people that think it's a bad idea but have no verifiable proof of such . Then you have those of us that have done it many times and have had no issues . That seems to happen a lot around here .
This isn't the first discussion we've had on this subject .
