What kind of oil?

[carnutcass]

I've run Mobil1 since I bought my 2002 GTP new and at 97,xxx it still doesn't use even 1/2 quart between oil changes.

[UKtech]

I'm with BNaylor on that one , Mobil1 all the way.
I've had turbos on the dyno that are almost seethrough and i've never seen Mobil1 break down whereas other oils have.

If you religously change your oil every 5000 km and are not racing between lights then non synthetic is fine in my opinion

[GaryFenza]

Mobil 10w-30 high milaege on my 03 GP GT with 116K

[tblake]

Originally Posted by 00GTP4ME

Ok moneybags! j/k.

Me? LOL!

Have you got a smaller pulley and downpipe yet Matt?

I just installed a DHP PCM from pfyc and it really woke up my GTP. especially in performance shift mode. Well worth the 200 bucks (I decided to keep my original PCM) Best thing about the DHP PCM is the fan turn on times. My car hardly ever gets above 190 degrees even in an hour of stop and go traffic.

I also ordered a 2.5" bolt in downpipe from ZZP. I emailed them and they said that both the 2.5" and the 3" will bolt into stock exhaust. But I read previous posts from GTP drivers who have reported possible low end torque loss due to not enough backpressure from running the 3". So I decided to stick with the 2.5" Maybe next week I'll have an exhaust shop put it in for me. I checked and my bolts are too rusted and I'm sure I'm going to break them. Plus maybe I can pay my bill with the old cat converter since its not plugged. LOL

[tblake]

Ok, back on topic. I've got a qustion for you guys.

Say I've ran conventional oil in my car since I got it. Next oil change I switch to synthetic....

Do I have to now stick with synthetic or am I able to switch back?

I thought I heard that once you run synthetic, you have to stick with it. Is this true?

Also, I heard that there is a certain type of synthetic that conditions seals and can actually stop small oil leaks. Anyone heard of this? What brand?

[UKtech]

Originally Posted by tblake

Ok, back on topic. I've got a qustion for you guys.

Say I've ran conventional oil in my car since I got it. Next oil change I switch to synthetic....

Do I have to now stick with synthetic or am I able to switch back?

I thought I heard that once you run synthetic, you have to stick with it. Is this true?

Also, I heard that there is a certain type of synthetic that conditions seals and can actually stop small oil leaks. Anyone heard of this? What brand?

No that is a myth you can switch back and forth,i've never seen any issues in my career.... although it really makes no sense to do so.

IMHO the key is to change the oil EVERY 5,000km or 3 mnts whichever comes first, you can push a little longer with sythetic

Some of the high mileage oils have additives that soften up the seals. Most brands do some kind of High Mileage oil ,Castrol and Mobil both do. Just stay away from additives that contain ptfe,that is just evil!

[tblake]

what does ptfe do? and how do I know if an oil contains it or not?

Thanks for the heads up!!!

[wlkjr]

Originally Posted by tblake

what does ptfe do? and how do I know if an oil contains it or not?

Thanks for the heads up!!!

Here's some interesting information on ptfe or teflon as some call it.

http://blackstone-labs.com/dec_07_eng.html

[carnutcass]

I've seen several high-mileage cars that developed oil leaks after the owner switched to synthetic. The theory is:

Sludge builds up over time allowing seals/gaskets to dry out due to lack of conditioning from oil. The synthetic oil helps clear the sludge which exposes dry, cracked gaskets.

I'm not sure how well the seal-conditioning synthetic works. I've never tried it.

[BNaylor]

With synthetic oil the biggest issue that I know of on SII 3800 engines with high mileage are the valve stem seals. Symptoms after switching over from dino to synthetic is high oil consumption and smoking out the exhaust during startup. A few members on AF had the issue. That is why I would not do it on high mileage engines.

[carnutcass]

Originally Posted by BNaylor

With synthetic oil the biggest issue that I know of on SII 3800 engines with high mileage are the valve stem seals. Symptoms after switching over from dino to synthetic is high oil consumption and smoking out the exhaust during startup. A few members on AF had the issue. That is why I would not do it on high mileage engines.

Which brings us to a question I've wondered about for a long time.......how many miles constitutes "High-mileage?"

[BNaylor]

Originally Posted by carnutcass

Which brings us to a question I've wondered about for a long time.......how many miles constitutes "High-mileage?"

Good question. I would assume the maybe the 80K mark if you go by what the oil companies say concerning high mileage oil marketed. One recent anecdotal case we had the member had around 110K miles when he decided to switch to full synthetic. Of course, the results were not too good. When I switched to synthetic in my GTP several years ago I recall the mileage was around 24K miles but it has worked out fine for me.

[tblake]

Crap, guess I shouldnt switch to synthetic then should I Bob, I've got 90,000 Miles on the clock...

I am using valvoline max life which supposidly is a synthetic blend. Got a small oil pan gasket leak, but its only down a half a quart between changes.... if that.

[BNaylor]

Originally Posted by tblake

Crap, guess I shouldnt switch to synthetic then should I Bob, I've got 90,000 Miles on the clock...

I am using valvoline max life which supposidly is a synthetic blend. Got a small oil pan gasket leak, but its only down a half a quart between changes.... if that.

Its really up to you Tim to make an educated decision. It may work out fine. Who knows. However, if you have existing oil leaks I wouldn't switch until the respective seal or gaskets are replaced first.

[wlkjr]

Originally Posted by tblake

Crap, guess I shouldnt switch to synthetic then should I Bob, I've got 90,000 Miles on the clock...

I am using valvoline max life which supposidly is a synthetic blend. Got a small oil pan gasket leak, but its only down a half a quart between changes.... if that.

Obviously, for my application and driving style, synthetic is not necessary. I've read several articles that state not to change over to synthetic on higher mileage cars because it could cause leaks.
If there's nothing wrong with the oil you use now, why change and risk causing problems, unless you just like repairing them.
To me it's kinda like not flushing an old transmission.