Switching to Synthetic

[Fishin4Life]

With all this talk about oil change intervals it got me thinking. I have three vehicles, a 1500 sierra, a neon, and a 2002 mitsu galant with the 4 banger. They all have around 100,000 miles on them. They all start fine in the winter except for the mitsu. If it gets really cold the mitsu doesn't want to start even with a brand new battery. Even in the summer it just seems to always turn over a bit slower than my other vehicles have in the past. Would switching to a synthetic oil help this and help cold starts in the depths of winter?

Can I switch a car with 100,000 miles to synthetic even though it has been run on conventional all its life? Thanks in advance. Any advantages/disadvantages to switching to synthetic at 100k?

[Scott K]

Yes, you can switch over anytime, yes if it is turning over slow in cold weather, and not in warm weather it will help, if its all the time, if you saying the engine cranks over slow, all the time then it may be a ground issue, power issue, or a starter going bad.

[Fishin4Life]

It is not necessarily slow under normal conditions, but just different than what I am used too, so seems slow to me. It starts just fine when warm and has started the same since I have owned it at 60k. Just doesn't seem to like the cold.

[theoilman]

In general, you can use synthetics in any "sound" engine - that is if it is not burning or leaking an excessive quantity. And the only reason then is it will be expensive to "oil the highway" with.

There is a difference between the different brands of synthetics about their cold performance, and it can be substantial. I have data available comparing the popular ones.

However, a word of caution, especially the GM engine with 100K on the clock. If varnish, gum or sludge is holding seals together synthetics will do a much better job of cleaning it out. The synthetic won't cause a seal to fail, but with a better cleaning characteristic it may reveal a tired or worn seal.

Another question you implied but didn't actually state, How do I change? With 100K on these engines I would recommend the use of an engine flush or cleaner to remove the existing gum and varnish first.

AMSOIL does have flush available as well as all the different viscosities. You didn't state specific model years, so making specific viscosity and product recommendations is impossible. E-mail me privately and I will be glad to help with specific recomendations.

[Valv]

I had a '92 Corvette with 135,000 miles, bought it used and neglected, toke it to dealer to have oil changed, they suggested going to synthetic since that was the OEM oil for the car.

Toke it home, and after 100 miles engine started knocking ( rod knocking) really bad. I then sold the car.

On the other hand I had a BMW with 203,000 miles, I switched to Mobil1 and didn't have a problem for many thousands of miles.

To me switching is worth it, but you have to be careful, since synthetics will "clean" engine to a higher level compared to dyno oil.

[Fishin4Life]

Oil man did you get my e-mail that I sent a while back?