I just replaced my 2007 HHR (152,000 miles) with 2006 HHR. The 2006 has 54,000 miles and I believe it has always had regular oil (at least I was told by the dealer that is what the they put in it when they changed the oil). He believed the car did not take synthetic oil since the car does not have Synthetic oil written on the oil fill cap. In my 2007 I always used Mobil 1 synthetic. Not that it will make any difference in your answers but my motor is a 2.4. So my question is can I make a permanent switch to Mobil 1 synthetic oil without hurting my motor? Thanks for any input you can supply. John

 

I would. I use mobile one in all my vehicles with no issues.

 

Swapping to Mobil 1 shouldn't cause any trouble, but because of the mileage and the unknown change intervals used by the first owner, I'd change the oil early after the first synthetic fill.

That way you'll catch and remove any sludge loosened up by the change in oils, and eliminate the possibility of a plugged oil passage.

 

Yes I prefer to use the synthetic Mobil 1 and I was going to keep the first fill of Mobil 1 for only a short period of time. I am not sure about the original owners use/type of oil but the dealer did put non-synthetic oil in it. I have only put 200 miles on it since I bought it Monday so I am going Saturday to get synthetic put in. And that is exactly what I was afraid of mixing the two would form some chemical sludge that plugged up something. Which is why I asked the question.

 

I might suggest adding something like SeaFoam in the crankcase for a few hundred miles before the first change (read the directions on the can).

Mixing Dino and Syn WILL NOT sludge anything up.(period).

 

I tried switching to synthetic after a few years (maybe 50-60K miles) and it drank the synthetic like it was water. It used a quart in just a couple thousand miles - so went back to conventional oil and it took a while for the oil consumption to return to almost normal.

Prior to synthetic trial, it used maybe a 1/4 inch on the dipstick in 5000 miles or so.

so if you do give synthetic a try, check the levels frequently.

 

Never thought of the SeaFoam idea, and I'm only just warming to the idea of even trying it. But as our in residence "knowledgeable skeptic", you're use of it Don will eventually see me trying it in something.

And you are correct, mixing normal and synthetic oils will not cause sludge, but I have found that changing from organically based oils to Mobil 1 did tend to "liberate" existing deposits.

Whopper's experience with increased oil consumption does occur, engines will create their own clearances as they break in, and some engines just don't "like" synthetic oils. Plus, synthetic oils can find their way past seals and rings much easier than Dinosaur juice.

 

I think I am starting to be a SeaFoam addict. I ran about 8 oz. in the crankcase for 12,000 miles, and I can see a difference. I think it loosened up a stuck oil control ring and helped clear up P0420.

It is pretty amazing that the "old mechanic's" tales stay alive. Early on the old guys were afraid to use Syn just because it was new, so they made up reasons that make no sense to scare everybody away. The only real reason to avoid Syn is the cost, if that's a factor for you.

I have noticed that Mobil 1 dissappears a bit faster than some of the other. I have no favorite, I get the DEXOS that is on sale. GM says; if it has the DEXOS label on it it is DEXOS. (DEXOS is a Syn specification, although I think some blended are available).

The actual thing to watch out for are the "high mileage" oils that contain extra Zinc, don't use them if you are burning oil. Zinc will poison the cat, as will most metals.

 

When I Got mine at 86k miles,I switched over to Amsoil (Dealer) everything in it now is synthetic,and working better then ever now at 117k

 

I switched at 60,000 miles and no issues or consumption problems, I run until the DIC shows 10 % oil life left about 3 to 4 months for me.