2003 BMW 530i Q&A

2003 BMW 530i Question: Is it harmful to mix synthetic and natural motor oil?

Have both 530i and 323ix. "fULL SERVE" attendant put 2 quarts of 10-30 natural in the 323 without asking. Will oit do any damage to the engine? -
Answer 1
NO, BUT If it was that low, you've likely exceeded the time factor or miles for the oil and it needs changed anyway. Unless you have a significant leak, I can't imagine being 2 qts low. If it were mine, I'd change it ASAP. I used syn-oil in my 1999 323i and it never leaked, but would use < 1 qt. by the time I changed at 10k miles intervals. KIA at 235k miles and still running great. My now newer 530xi does not loose a drop up to 8k miles between changes on BMW approved Syn-Oil with 68K miles on the odometer. -
Comment 1
Thx. Yes, it was due for a change --to synthetic, about 10K between changes -- 125K on the odo. Doesn't burn, but it uses oil. Similar situation with 160 hp aircraft engines I fly -- oil is really the lowest type of insurance. Thx. -