Mobil Synthetic Oil question...

[Mark D]

When getting my last oil change, I decided to try going with Mobil 1 oil instead of 10w30, since I had a $10 coupon. I have never used synthetic oil before and the kid at the oil change place did not disagree.

Ever since, my car smells like a foundry. My engine is burning oil and it is quite annoying. I don't notice any performance differences, nor does it seem to exhibit any problems other than the burning. No smoke is coming out the exhaust, or at least it is not burning in large quantities. It's not burning up like crazy, but I sure smell it strongly. I've driven around 300 miles now since the oil change.

I've got 116,000 miles and have never used synthetic oil in this engine. I've never had a drop of oil burn as I am full at every oil change, which has been done religiously every 3,000 miles since I bought the car new in '98.

So, am I doing any damage? I am about to take it back and put in dino oil. I have heard that the seals and gaskets can leak, but is there any other risk at this point?

Thanks in advance,

[hot95camaro]

I've asked a couple of my mechanic buddy's about this and they told me that u shouldn't run synthetic unless u've been using it from the start. This is because the seals are old and the synthetic can get through the small cracks and holes that develope thus leading to some unwanted burning.

[Mark D]

There are a lot of topics on this board relating to the use of synthetic oil. Based on the smell of burning oil and the potential risks associated with using a synthetic oil in an older engine, I am going to change the oil back to 10w30 ASAP. I am hoping that 300 miles would not have caused the seals to become leaky, but this topic seems to be a debate.

[MrCoffee]

why run synth? it only has sopas and detergents to help further clean your engine. And the LS1s use it. I switched to synth after my car had already had 25k miles on it. the only thing bad I've heard is that if you keep switching between normal and synth it can cause problems. but thats only in the extreme. I personally wont go back. LS1s come with it from the factory for a reason.

[grayman]

he could have spilt oil on engine. Sometimes that stuff takes a long time to burn away.

[Nicklz]

I always switch my cars to mobile 1

IMO, it's never to late to switch to syn. I'd say the guy who changed the oil probably have spilled/pooled oil on the engine.

[brink]

m i think the dude that changed my oil used 10w 20... or maybe it was 10w 30? AH.
i feel like a newb, wats the difference?

[Mark D]

I will drive my car a few more hundred miles and will see what happens. It is possible that there is some spilled oil on the engine that causing the odor, but it seems more likely that the thinner oil is burning as I drive. (I've never smelled oil burning after ANY oil change in my life). I smell it everywhere - whether the windows are up, down, or if the cabin fan is turned off. It's just annoying and it needs to go away. My main concern, as mentioned in my first post, is that this could actually be dangerous for the engine or for the seals.

Instead, maybe I have a problem with my nose??

If the Mobil 1 continues to burn, I'm going to switch back to regular oil -- and soon. I'm not in the market to replace anything or have any repairs done to allow me to use Mobil 1 (I could care less about running synth oil, honestly, as long as my engine is well-maintained). My expectation is to get 160,000 miles out of this car, and I have maintained it appropriately since day 1.

[98Camaro3.8]

It's widely accepted that it's not good to switch an engine from normal to synthetic oil at a high mileage. I personally wouldn't switch above ~30K.

FWIW, I use Mobil 1 with no problems, but I started long ago.

[Mark D]

Well, I made the switch back to 10w30. I got some strange looks at the oil change place, but the burning smell is now gone.

So, if any of you have a gently used 3800 Series II with 100,000+ miles, I'd suggest NOT using synthetic oil.

[98Camaro3.8]

Another FWIW....synthetic oil is still of the same weight as dinosaur oil...10w30, 5w30, etc. I run Mobil 1 in a 10w30 weight.

[badbird02]

if you got problems with the weight use 10w-40 i did that in my storm and it never burned oil again. synth is WAY better for your engine its like this look at what conventional oil is made of (dino and okd crap) and what synth is made of (chemicals made in a lab). synth is way more pure.

[mjparme]

Originally posted by 98Camaro3.8:
Another FWIW....synthetic oil is still of the same weight as dinosaur oil...10w30, 5w30, etc. I run Mobil 1 in a 10w30 weight.

Thank you for pointing this out, I was getting real annoyed reading through the thread talking about switching from Mobil 1 "back to 10w30". I was going to post the exact same thing.

Synthetic oil doesn't cause leaks, it simply exposes leaks that were already there; however, they were clogged up by sludge and stuff. The synthetic oil cleaned up the sludge which exposed the leak.

If you start leaking after synthetic you already had issues and just fix those issues rather than blaming the oil.

I switched to synthetic (Mobil 1) in my 99 at 55K and had absolutely no problems.

I run 5w30 in the winter, and 10w30 in the Spring (I may have that backwards, I would have to look it up in my owners manual to be sure). I simply follow the directions in the owners manual as to which weight of oil to run. I live in a cold climate so I switch oil weights in the winter for easier cold starting (as recommended in the manual...actually the manual recommends synthetic for winter time in a cold climate).

[Mark D]

Thanks for the clarification between Mobil 1 and 10w30 - I did not realize that until now. (As you can tell, I don't know a lot about this sort of stuff).

My book is closed on this issue as regular oil is what my engine AND nose is used to.

[terminaldegree]

I switched my bird over at 30K.
I switched my g/f's lesabre over at 70K.

Neither one had leaks to begin with, neither one does now.

Given the cost of the stuff, I certainly wouldn't switch it over into an engine that would leak or burn a lot of it.