Will mixing synthetic with conventional oil cause a gel to form?

“I mixed Mobil 1™ with regular motor oil. My mechanic told me I should not do this because it forms a gel; is this true? I did it on three Honda Accords – a 2003 with 40,000 miles, a 1990 with 201,000 miles and a 1992 with 190,000 miles.”
Jordan Mayer, Cape Coral, Florida


In general, oils should be compatible with each other. It is not likely that you would form gel by mixing the two oils. However, we would not recommend mixing oils as a general practice because oils are complex mixtures of additives and base oils that can be destabilized. Also, why reduce the outstanding performance of Mobil 1™ synthetic motor oils by adding “regular oil”? Is it economics? You would be better to run all Mobil 1 synthetic motor and run it longer than mixing it with “regular oil.”


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