Oil question

[DetroitNut90]

Cliffnotes version: What happens if you go from using synthetic blend motor oil to conventional?

Full-fat:

I took my car to the dealership yesterday to get some work done (mistake 1). Back when I had the recall work for the engine fire concern on the 3.8L V6, I took my Intrigue up to the local Chevrolet-Buick-Pontiac-GMC-Isuzu dealer to have it taken care of. Everything went fine, I got my car back and was happy as a clam that I wouldn't find it and/or myself engulfed in flames one day. To further make me happier, I received in the mail around the beginning of July/end of June a letter from the dealer thanking me for choosing them to work on my car. Included in this letter were a series of coupons, notably, one good for a free oil change and another good for a free diagnostic service on a vehicle system. Since I was due for an oil change and my climate control system has been acting wonky for a little while, I took off work yesterday to have said work done.

When I sat down with a guy to take down my information, I began to explain to him the problems I was having with my climate control. Before I could give him a good description of what was happening, he waived his hand to silence me, saying I didn't need to continue. After asking me something else, I guess I was too long winded for him because he waived his hand in the same manner again. We repeated this unpleasant exchange for a little while longer, until he told me he had everything he needed from me, and showed me to the lounge. Before I left, I made sure to ask whether or not the coupon for the oil change coupon covered synthetic blend oil. He told me he wasn't sure, didn't think it would, but would check with a mechanic to be sure. He then asked me if I still wanted the oil change done, even if I had to pay for synthetic blend. I told him yes, I did, that I would pay for it if I had to (mistake 2). He said ok.

For the next four hours, I waited in the lounge of the service department. A different man showed up this time, and after introducing himself, took me back into the service bay. He explained to me what was wrong with my climate control, that the left and right actuators and the mode vacuum motor are bad. He gave me an estimate of 6 hours and $1,167.05 plus an environmental fee to fix the problems. I told him that I would have to talk it over with my parents, and declined the service. Reluctantly (I knew he wanted me to authorize the work), he told me he'd have everything put back together and ready to go in 15 minutes, and walked me back into the lounge. On the way there, he told me that the oil change was done at no cost to me, but that he would have to charge me $93.88 for the air conditioning diagnostic, which was free only until a point. I paid the bill and left (mistake 3).

When I got home, I read over the work order and realized, not only did they put the wrong weight of oil in the car (the engine itself says it takes 10W-30, they gave me 5W-30), but they put conventional instead of synthetic blend. I've been raised hearing "once you start putting synthetic oil in your car, you can't switch back to conventional oil," so this made me concerned. A friend of mine who is knowledgeable in automotive mechanics told me that I shouldn't have to worry about the oil unless it's over 90* outside and I'm not moving very fast. My dad also said that he didn't think it would cause a problem, though he didn't know for sure.

So, my question is the same: What happens if you go from using synthetic blend motor oil to using conventional? Should I get the stuff out of the engine now, or is this something I don't need to worry about?

Insights are appreciated!

[fightingbee]

You'll be fine. You can even switch between conventional and full synth. without issue. Also, about ~80% of a Synth. blend is from the same base stock as SM grade conventional oil IIRC, so to the engine it is not all that different.

[ShadowDog]

The issue of using 5W30 instead of 10W30 won't make any difference unless it's getting cold outside any time soon. Simply explained, 5W30 flows better when the temperature drops. The only issue of any concern would be with excessive heat that would break down the viscosity modifiers in 5W30 to enable carbon deposits to form on the valves; however, by excessive heat, I refer to a lack of coolant, prolonged idling or high-sustained RPM. These things aren't such a big problem with oil these days. I know that up here in Canada, I ran 5W30 in the Monte Carlo simply because of the variable temperatures. In your case, it'll be fine through this driving cycle - unless you really want to put in a synthetic blend and need to change it out then.

Yeah, the dealer really dropped the ball, but there's no damage to result.

[daves87rs]

First, the oil myths you hear are complete BS.

You can go from dino to synthetic oil all day long if you want, as it is not going to hurt the engine. Today's engines are much different than those even 10-15 years ago. The only worry would be if you had a REALLY high milage engine (and a bit abused) might leak a bit if you went from dino to synthetic. On your 3.8, you are more than fine.

Second, the 10w30 will be fine...will will notice a decrease in MPGs though (not much) This engine ran on 10w30 for years...and I'd agree with your friend. Unless it was super hot or something, and even then, your car would be a little pokey.... You could run 0w30 too, or even 5w20 if you really wanted to. The engine would run fine on all the the above.

Third, take the car to some place that knows cars. I'm betting it can be done much cheaper than that....

[daves87rs]

The issue of using 5W30 instead of 10W30 won't make any difference unless it's getting cold outside any time soon. Simply explained, 5W30 flows better when the temperature drops. The only issue of any concern would be with excessive heat that would break down the viscosity modifiers in 5W30 to enable carbon deposits to form on the valves; however, by excessive heat, I refer to a lack of coolant, prolonged idling or high-sustained RPM. These things aren't such a big problem with oil these days. I know that up here in Canada, I ran 5W30 in the Monte Carlo simply because of the variable temperatures. In your case, it'll be fine through this driving cycle - unless you really want to put in a synthetic blend and need to change it out then.

Yeah, the dealer really dropped the ball, but there's no damage to result.

What about using 0w30 up there?

[Intrepidation]

What an unprofessional dealer. I would file a complaint about the attitude of the tech who kept cutting you off, as well as the fact that they did not put the oil you specified in your car.

[DetroitNut90]

Ah, well thanks for the advice, everyone! I took the Intrigue to the Outer Banks and back 2 weeks ago, no problems to report.

I think it's kinda late to call up and complain about the quality of service I received, but I'll just be sure to take my business elsewhere next time.

[daves87rs]

Good to hear that she is doing fine!