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To Synthesize or Not to Synthesize

I have a 2006 Mini Cooper ‘S’ which I have taken to a local, seemingly reliable, mechanic for oil and tire changes for a few years. They fill it with SEMI-synthetic oil on each oil-change.

Today, another respectable, closer-to-home, ASE-Certified/Master Tech-staffed service center informed me that their three sources, including Chilton’s, specify FULL-synthetic for my car and nothing else. A quick call to a Mini dealership echoed the same.

My questions:

1) Should I switch to the FULL-synthetic, now?

2) How often should I expect to change the oil with FULL vs. SEMI?

3) Am I sending my car to an early grave?

Use full synthetic, changed as recommended by your owners manual, more often if you like.

Your owners manual should have this spelled out too.

What I hear…BMW’s require full synthetic. If so then you should use it.

Assuming the owner’s manual specifies synthetic oil, then you must use synthetic or risk damage. I would switch it out as soon as reasonable possible if the wrong oil is in there now.

Synthetic does not mean longer change intervals. Check your owner’s manual. Follow the recommended oil change schedule found in the owner’s manual.

Synthetic may allow for longer oil changes, but it also may not. The manufacturer has done the test, use their recommendation.

Semi-synthetic should be used as a slight premium non synthetic.

Yes, you should use full synthetic oil in this car. It should have had full synthetic from day one.

Read the owner’s manual to see how often it should be changed. DO NOT wait longer than the change intervals in the manual.

Here’s the real question:

How long have your oil changes been on the semi-synthetic oil?
Also, how hard are you driving the car.
Which brand and version of synthetic oil has your shop been using?

It is entirely possible that the semi-synthetic meets the specs for the Mini engine, but unless we know what the oil is, there really isn’t any way to know for sure.


Thanks for all the valuable feedback and suggestions.

After further research, I have gone back to FULL-synthetic. Thank goodness the 20,000-mile diversion to SEMI didn’t harm the engine. She’s running well.

(By the way, the SEMI-synthetic was Kendall GT-1.)

Happy Motoring!