high miles, what oil?

[flowsv6]

i just got a 95 trans am with 140k miles, still runs strong and operates really well. i know its been gettin havoline with the oil changes, but i usually use mobil 1 in my cars. would it be wise to use a fully synthetic oil now, or even a half syn., or just stay with straight conventional? please help me out.

['98 BlackBird]

I use Penzoil High milage for the car. It has 110K on it

[Silver 99 Camaro]

If it's had conventional stay with it. Although I have heard many opinions on this, synthetic may leak since the molecules are smaller than dino oil. Especially with that many miles, the gaskets are not going to be pristine. I agree that a high mileage conventional oil, like Pennzoil High Mileage or Valvoline Max Life are the way to go...and cheaper than synthetic. They also have additives that will reduce valve guide leaks and that will condition seals.

[HBHRacing]

you CAN switch to synthetic. it will NOT cause leaks or burn off. The only mildly adverse effect that I have not found proof of being dissproved of is that an older motor that is very dirty can be washed out and have pump screes and pasages pluged from synthetic. I assume that If I keep looking harder I could find this will be proved as a myth as well. It's safe to switch.

[BLLDOGG]

i have to disagree HBHRacing. i do believe that with a high mileage car, you will spring leaks going to synthetic. mine did it and alot of others have too. kind of different but my moms boss put synth. in his plain and it poored oil. when he went back, it stopped.

[HBHRacing]

go do some research as I have. Don't trust what you think you see, look at what tests show. Synthetic oil is compatable with all seals, thats something that conv oil can not even say.

[terminaldegree]

Not to diss anyone here, but you might want to try posting this at:

www.bobistheoilguy.com

There is a section for your question specifically, as well as used oil analyses for cars with your engine using various brands of oil. Be sure to tell them how you intend to drive the car, and how long of an oil change interval you desire.

There are people here who ACTUALLY know the answer to this, and then there are people who THINK they know the answer to this, and just post anything off the top of their head with little actual knowledge.

Sorry, I can't help with your answer. My 3.8 is too young to be helpful for your question [37K and using Mobil 1 10W-30]. I have had high mileage cars, but I never tried switching to synth with them.

[Fredless]

My old 94 3.4 had 130k on the clock when I bought it, brought her home.

It had been ABUSED (I got it for dirt cheap), oil hadn't been changed in about a year and only had regular dino oil in it. Switched to M1 10-30 the next day, gave a full tune up and the car ran great (no leaks) until the day I sold it.

The only thing it did was cough a little blue smoke on cold start ups in the morning and every now and then while sitting at a red light. But what could have I expected? It had around 145k HARD miles on it by the time I got done with it, I had fun with that car my senior year in high school. How I wish I did not sell that car now...it was bullet proof.

[Turbo V6 Camaro]

Originally posted by BLLDOGG:
i have to disagree HBHRacing. i do believe that with a high mileage car, you will spring leaks going to synthetic. mine did it and alot of others have too. kind of different but my moms boss put synth. in his plain and it poored oil. when he went back, it stopped.

the leak was already there

thats just proof how bad reg oil sucks and don't do its job

[stonny9]

my 93 3.4 has 145000 miles and i just switched to valvoline full syntethic 2000 miles ago and no leaks yet. for about 15000 before the switch i used valvoline max life.

[Nicklz]

96 3.8, i bought mine with 132,000. Drove for couple hundred miles and switched to mobile one/ synthetic, i'm at 140,000 with no leaks.

I personally think that syn. won't cause a leak, but if one was present before it may become more noticeble once syn is in. Due to the fact synthetic is smaller particles and does a better job of circulating through the engine, unlike dino oil which has a tendency to "junk up" after it has used up the additives in the oil. One of the reasons why some people may not have noticed the leak before they switched. Just my 2 cents...

[HBHRacing]

The particles are not really smaller. They are just uniform. Conv oil has particles of many different sizes. The small ones can just burn up and thats where you get deposits.

[Silver 99 Camaro]

read these and search for other threads on this site. very informative in regards to synthetics. most think they are not worth the extra price as well as the other gimmics like blends, etc. only benefit are longer oil change intervals. High mileage oils are recommended for high mileage cars.

http://theoildrop.server101.com/cgi/...c;f=1;t=007115

http://theoildrop.server101.com/ubb/...=007672#000000

http://theoildrop.server101.com/cgi/...c;f=1;t=006878

[ARTFART]

Originally posted by '98 BlackBird:
I use Penzoil High milage for the car. It has 110K on it

I use that stuff on my car , and I am very pleased with it . My car use to burn a little oil , I dont think it burns a little any more .

[lon elliott]

my 97 has 96 K miles on it, when i switched to synthetic on the last change i sprang a rear main seal leak, dont know if its the oil, or the miles or the fact that its pretty common in F-bodies. But im going to keep mobil 1 in it. Has to be better for the car.