Switching to Synthetic Oil on Used Car?
 

I know this is not Cobra related, but it would apply to any engine. Would there be any downside to switching to synthetic oil on a 100,000 mile engine that has lived it's whole life on regular oil? Car is a 2001 Chrysler 300-M with the 3.5L. Will the synthetic oil "clean-up" the inside of the motor IF it is sludgy? (I'd bet the inside of this engine is very clean though as the car was meticulously maintained). I just like running synthetic in all my vehicles compared to regular motor oil.

Would not hurt anything only concern would be if engine is sludged u and the synthetic dissolves and plugs the filter

Do it. Mobil 1 High Mileage Oil might be the right choice. I have done the same thing many times & subsequently put tens of thousands on the engines without issues. As noted above, an oil and filter change after 3,000 miles would be a reasonable precaution against newly dissolved sludge.

However it is likely that a quality conventional oil (with detergents) will have prevented any sludge built up.

Z.

If there is any kind of leak (no matter how small) synthetic oil will find it. Other than that there's no problem.

Bob

I certainly agree that if an engine is leaking with conventional oil, it will continue leak with synthetic oil. However I have never had an engine develop a NEW leak as a result of switching to synthetic oil. There is a lot of anecdotal information to the contrary, but in my experience, no leaks. I have switched to synthetics in the following vintage Ford engines over the years: 200 ci I-6, 260, 289, 390, 427, & 428 V-8's. Also have used synthetics in my SVT Focus & Taurus, Karmann Ghia, Triumph TR-4 & Spitfire, & Jaguar XKE.

Z.

In the past, leakage was a problem. As gasket were exposed to dino oil, they swelled. When people would switch to syntheitc, they would shrink and leak. That's not the big issue now as it once was.

Syntheitc oil has two distinct advantages over dino oil: Better heat tolerance, and longer drain intervals. If you don't need those two advantages, don't waste your money.

There are only 4 true synthetic oils on the market. And Mobile 1 is not one of them.

Please Bob - do tell! I've never heard this before.

I used to run Castrol Syntec, & then started using Havoline 100% synthetic years ago on my vehicles. Here's a quiz (something I discovered years ago): is synthetic oil flammable?

BTW, I have seen NO evidence of oil leaks so far on this car.

Thanks, -Eric

I didn't have any leaks until I switched to synthetic Castrol Edge. Right at the bottom of the scattershield. Wipes up easily off the floor.

Mobil 1 high mileage has a seal conditioner so that should not be a problem.

by far the best feature of synthetic oil is reduced friction, which in turn reduces wear.

whether or not Mobil 1 is a true synthetic is mainly an advertising issue. The additive package is what determines if an oil is synthetic or not. The base stock used have no bearing on the matter. The manufacturers that tout their oils as being superior based on different base stocks may or may not have a legitimate point. But that alleged superiority is not related to the product being or not being a true synthetic.

Are there better synthetic oils out there than Mobil 1 ? Possibly, but not proven to me for my needs. Are these oils more expensive than Mobil 1 ? Certainly.

Z.

AFAIK, there are only 4 true synthetics on the market: Amsoil, Redline, Rpyal Purple, and another I can never remember the name of.

Not true at all. It's a trick of marketing types and lawyers that make you think M1 is synthetic.

A true synthetic starts with a PAO base stock, no dino oil. Then it's further refined, and the package is added. The key is there is no dino oil.

Oils like M1, QS, etc start with standard dino oil. Then they refine and add until it meets the legal requirements as established by the courts to be allowed to use the term "synthetic". It's a marketing trick, don't fall for it.

However, that's not to say they are bad oils. They're not. They do perform better than standard dino oils. But not as good as a true synthetic. Most people don't need the performance of Redline or RP. If you can get M1 pretty cheap, there's no reason not to use it. This is not a case where you get what you pay for.

As for reduced friction, that's true. Semi-synth's are better than dino, but not as good as true synth. If you're racing and need every last hp, it's worth the expense for a true synth. If it's a street car that gets less than 5K miles a year, you'll get the same performance using standard Penzoil (or maybe wallyworld) and changing it once a year.

My 427 cobra has a 428 FE engine, and my engine builder said that after 1,500 miles on the engine, it is OK to use synthetics.
Otherwise; if you use syn too soon, you would prevent the break in process.
I also heard much discussion about oils that contain zinc, to help the scoring of flat tappet camshafts in vintage engines.

Don

the forums on http://www.bobistheoilguy.com/ are pretty entertaining, and no one takes it all too seriously......

http://www.bobistheoilguy.com/cms/in...tid=35:content

this one of the best lines: "...... over half of all NASCAR teams are using Mobil 1 technology; Mobil 1 is also a technology partner with the Vodafone McLaren Mercedes Formula 1 team....."

Z.

OK, since nobody took me up on the question about whether or not synthetic oil is flammable, I'll tell you my findings (I thought this was interesting). I used to burn my drain oil back in the days when I was changing my oil regularly - the best & most environmentally friendly way to get rid of drain oil. Anyway, I could NOT get the syn oil to burn - no matter what! It would boil, but not ignite. I then tried burning a paper towel dipped in it, & it also would not burn. Then a few years later, I had my oil changed somewhere & paid extra for syn oil. Later when I got home, I tried the burn test & it lit right up. I figgered I got ripped off. Anyway, on my 300M from now on, I'll be supplying the oil at the oil change place.

And I have heard about syn oil finding leaks, or even "creating" them. Not sure if I believe the latter. Also have heard that it will loosen deposits inside a motor if there are any, & that could be bad. I'm still not 100% sure if I'm going to switch. On a new car fine, but I'm a little apprehensive on a 100k+ engine.

Amsoil reccommends using engine flush (follow the directions to the letter) on higher milage engines when converting to synthetics.Then change filter a couple of times.Heavily sludged motors?yikes! your on your own there.