Hi, folks:

I got confused - one friend told me it's OK to use synthetic oil for old car (actually, he is using synthetic oil for his Nissan '93). But, last week I asked the mech to change the oil - using synthetic oil. But, he insisted that synthetic oil is not good for old car. He said, if there is scratch in the engine (? why), synthetic oil will make it even worse. I am really confused. And, he said, once you switch to synthetic, you can't go back using the normal. But, this is fine for me.

Now, I need more inputs. Is it good to use synthetic for my volvo 240 DL, Wagon, 139000m? Why or why not? If yes, please recommend some brands. Pros and cons..... Thanks!

Shawn
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90' 240 DL wagon 138k

There were a few oddball synthetics (including some attempts by major oil manufacturers) that did create a permenant compatibility problem if installed in an engine ( with some even a small residue in the engine would react chemically with other lubricants and turn the whole mess into gelatinous goo or almost water consistincy), a couple of them were pretty decent racing oils. but that was over 20 years ago. I do not believe any of these are still on the market.
I started selling Amsoil around that time and had to work around the bad reputation of other lubes all the time especially among racers who had had the bad chemistry experiences.
You also had some people trying to use synthetic jet engine oil in cars...bad idea ( don't be tempted when you see the stuff in a military surplus lot for $0.15 a Qt.) excellant heat dissipation qualities, but lousy film strength and little if any detergent.

It's OK to switch older engines , just flush it first.
I switched my '90 at about 125,000 , and my '84 diesel at about 224,000 mi.

As long as your car is mechanically sound and has no current leaks synthetic oil should be the oil of choice.

Dunno, what he meant by "scratch"???

The whole "can't change back" thing is a huge myth. I'm not sure who started that one, but of course you can change oil to any brand/type you wish at any time as long as the oil meets the requirements for your car.

A 1990 is NOT and "old" car and 138,000 miles is not a lot of miles. Many have changed to synthetic oil at 200K+ with only good things plus a reduction in oil consumption after the initial cleaning effect of the synthetic is over - to minimize this I recommend a good engine flush.
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www.fidalgo.net/~brook4

Sure enough, the engine is still very strong. But, there is leak, very slowly. For 3000 miles, I never need to add 1/10 quater oil though. Why the leak is an issue?
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90' 240 DL wagon 138k

If you have an oil leak, prior to switching to synthetic, the leak will almost always get worse with the synthetic, due mainly to the flow properties of the synthetic. These "flow easily into tight spaces" characteristics ARE a good thing for lubing your engine......

One thing to add also is that synthetic oil is actually good for the seals, so if your seals are good to start with or you renew the leaky seal it will last longer.

Where is the leak?....sometimes if the leak is slow, the seal will swell slightly with synthetic oil and slow/stop, but this is rare. Best to fix any leaks regardless of lubes....best for the environment.
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www.fidalgo.net/~brook4

You might want to find another technician--
Synthetic oil works fine in my 85 240turbo, my 85 Saab 900Turbo, my 88 Saab 9000T, and my 1990 Dodge van. Matter of fact it has worked well in all my cars for the past 25 years. Most of these were previously registered and had about 100,000 mile on them before I bought them and changed to synthetic.

I think that mechanic is far more of a threat to the long term well-being of you car than is either oil. Synthetic is fine for your car, unless it leaks out at a rate that is to much for your wallet. Mechanically, as a lubricant, it is certainly superior.