Break-in, Synthetics, and Oil Consumption

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Dec 20, 2002
The coal hills of eastern PA
For those of you who believe putting synthetics in a new engine could cause the engine not to break-in properly, I have the following question:

I have a 2003 Saturn that I switched over to M1 10W30 when it had 2000 miles on it (it has 8300 now). I religiously watched the oil level through the oil change interval (I wanted to change it at 6000 mile intervals). The oil level stayed somewhat constant from 0-4500 miles (in the O.C.I.) but then dropped rather quickly from 4500-5100 miles where I needed to add a quart. If I would change back to conventional oils for a change or two, do you think I could get the oil usage to go away (engine would wear-in properly)? The only way I could think of why the oil level dropped so much after the 4500 mile mark was if the oil thinned out. What else could cause that?
I know I could run an oil analysis but I would rather not since the car is so new.

When breaking in a new engine be it dino or synthetic it is always good to change the oil at short intervals. The longest would be 3000 miles.
So I think you need to do several quick changes with whatever oil seems good to you and then back to the synthetic. Mobil 1 is a rather thin 10w30 so you may want to try Amsoil if you see consumption after break-in. Yes your engine could use up the oil in 4500 miles during break-in.
In breaking in my miata I changed at 700 miles
3700 miles and 7000 miles with Castrol GTX. Then went to synthetic. Zero oil usage during 7500 mile changes. It appears the engine did not fully break-in until 20,000 miles as the milage jumped from 27mpg to 29mpg at that point.
Just keep going with the Mobil 1. A slightly thinner oil is better during break-in anyway. You might want to consider the 10W-30 Mobil 1. I really have no problem with the Amsoil if you are so inclined. I just doubt if it will make a lot of difference. But I could be wrong.

I have broken in a number of vehicles in the last few years with Mobil 1 10W-30 doing the first oil change at as little as 30 miles. My second is usually at 4 to 6 K. I change filters at at least 3 K intervals though. I have had zero problems or oil burning/using issues in 4 vehicles.
The oil dropped most likely due to evaporation, called volatility.

The oil burnt off from the heat generated by the engine. All oils do this, some are better are it than others mostly due to the formulation and quality of the additve package.

Thininy out has nothing to do with it. I don't know where that idea comes from that oil thins out.
I don't believe that synthetic oils stop or delay break-in. If your oil consumption was due to inadequate break-in, your consumption would have been high at the start and gradually taper off. You're seeing just the opposite. My theory is that the rings are carboned up and stuck. I understand that Saturn's are known for this. Maybe some Auto-RX would help.

No, I have been driving the car the same since I bought it.


Is this to say that the additive package was used up in M1 10W30 in 4500 miles of driving? I drive like a grandmother. I drive about 18,000 miles a year and the vast majority of it is highway and rural driving. Hard to believe but possible I guess.


I don't think my car needs Auto-RX with 8000 miles on the odometer! I can't imagine the rings are carboned up after 8,000 miles and 6,000 of them were with Mobil 1. Besides the Ecotec is Saturn's "newer" engine that doesn't have the same oil burning and sludge build-up problems as past Saturns engines(at least that is what I am told).

[ April 29, 2003, 12:27 PM: Message edited by: ryansride2017 ]
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