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Use of the wrong type of oil

Relevant Information: Pontiac Solstice GXP 08 (turbocharged), purchased new, current mileage 31K. It has never been ‘abused’. It has been on four 1K to 2K round trips. For about 4 months it was used as a daily commuter. It has had 8 oil changes.
Problem: From 3K to 29K miles, non synthetic oil was used. (My mechanic used the wrong oil, I missed that the wrong oil was being used.)
Question: It is reasonable to think that the engine has escaped damage? And if not, what damage could have resulted and how will it manifest itself? Is there anything that should, or can, be done now?

Your oil was changed about every 4000 miles. There should not have been oil breakdown in that short time period between changes. Have the engine ever overheated? If not, you are probably OK. What is the recommended oil change interval for your Pontiac?

It’s possible that some oil has broken down into coke or sludge from the high temps in the turbo.
You’ve been changing the oil about every 4000 miles, which is fine even with dino if you’re not winding up the turbo often.
If there are no symptoms then no passageway or other important area has clogged, so using synthetic from here on out will clean things up.
It’s often said that synthetic oil is more aggressive at cleaning deposits, so with that first fill of synthetic keep an eye on the dipstick.
If the oil gets really dark/black change it early.

+1 to @‌circuitsmith, Highly unlikely any damage is done. Go forth and use synthetic and all will be well.

If youre really worried about sludge, have the valve cover pulled for a look-see. I strongly suspect you have nothing to worry about. Sounds like a nice car–enjoy it!

If you were using conventional 5W30 instead of full synthetic 5W30 in the early life of the engine then I see no potential for damage as both of these oils have a very similar additive package. The synthetic oil may clean better but the engine was probably too new to even worry about that.

A lot of Saturn owners refused to use synthetic motor oil even though GM recommended it. There were no obvious repercussions.

The owners manual states that synthetic 5W-30 oil that meets GM standard GM4718M is required.