Will synthetic oil cause clutch slip?

[1_v8_merc]

I got 140k on a highly abused camaro, which calls for synthetic.
I've used nothing but supertech 5w30-Regular oil.
So you can probably guess my views on synthetic(which really isn't synthetic anyways)

But you NEED TO USE DIESEL oil in your GS, because of the wet clutch system.
It will probably slip if you don't.
(there are people here that report no slippage with car oil...but it's Far from the majority.)

[koolaid_kid]

Actually, it is the extra additives that provide better shear protection for the gearbox that make diesel oil better. It is the "energy conserving" additives in automotive oil that make the clutch slip.
And synthetics really only provide longer oil life, nothing else.
And they come in two flavors - full synthetics and blended.
I don't waste my money on them, even in my turbocharged TransAm. I just change the oil religiously.

[Nessism]

Actually, it is the extra additives that provide better shear protection for the gearbox that make diesel oil better. It is the "energy conserving" additives in automotive oil that make the clutch slip.
And synthetics really only provide longer oil life, nothing else.
And they come in two flavors - full synthetics and blended.
I don't waste my money on them, even in my turbocharged TransAm. I just change the oil religiously.

Yes, the main thing with synthetic is it resists shearing down so it lasts longer. You can extend your change interval to offset the high cost. Another thing synthetic does well is resist thinning under extreme heat. A good feature for an air cooled motorcycle that gets stuck in traffic during the summer. Another application where the heat resistance would be good is feeding a turbocharger which gets super hot. Particularly some of the older type that didn't have water cooling.

[mrbill5491]

My color purple lol...

[sedelen]

And synthetics really only provide longer oil life, nothing else.

Unfortunately don't agree. Synthetics are much more superior to conventional oils. I once read an independant study where they ran two engines 100K, one with synthetic (after the engine was broken in) and the other conventional. Then they tore apart the engines. The sythetic oil engine still had cross hatching in the cylinders, the oil pan was spotless, gas mileage and horsepower increased (not much, but still) and in very cold weather synthetic wouldn't gel (had to use it in Alaska). The two con's I had with it, is if there was the potential for a leak, synthetic would find it, and it costs more.

http://auto.howstuffworks.com/synthetic-conventional-motor-oil.htm

http://suite101.com/article/synthetic-oil-vs-conventional-motor-oil-a136539

[koolaid_kid]

O.K. I have the original engine out of my TransAm sitting on an engine stand in my garage. (I replaced it with a fully forged turbo engine.) It has 40k on the clock. I pulled the heads off and there are still cross hatches in the cylinder bores. It spent 20k on a 5 p.s.i turbocharger. Using conventional oil. So, I will always use conventional oil, but certainly feel free to use the synthetic if you wish.

[tkent02]

I have seen several high mileage engines with all of the crosshatch visible, an Opel at over 350,000 miles, several BMWs at 2xx,000. My first GS550 at about 120,000. Even the rings were not worn at all on the 550.

I have never seen this on engines running non synthetic oil. Usually they are through the cross hatching and actually have a wear ridge before 100,000 miles, although the modern FI engines probably don't wear as fast.

Still I run the regular Rotella in everything now, I don't end to keep things long enough that I care all that much about engine wear.

[sedelen]

O.K. I have the original engine out of my TransAm sitting on an engine stand in my garage. (I replaced it with a fully forged turbo engine.) It has 40k on the clock. I pulled the heads off and there are still cross hatches in the cylinder bores. It spent 20k on a 5 p.s.i turbocharger. Using conventional oil. So, I will always use conventional oil, but certainly feel free to use the synthetic if you wish.

Actually I use both, synthetic in the 1000 and conventional in the 1100 since it's more prone to weeping running at higher temps. But I did use Mobil 1 in my Skunk in '79 when it was a fairly new commodity, and for the life of me I couldn't figure out where the oil went, didn't leak, just dissapeared. I used it during my x-country trip and when I took it to the shop for a check-up I asked the mechanic about synthetic oil. He looked at me and said, "where does it go?" so I changed back to conventional. I figured it just blew it out the breather.

[koolaid_kid]

I have read that synthetics have a higher tendency to leak thru small cracks than conventional oil, but I have never seen statistical data to back it up.
I have a friend that owns a 2002 WS-6 TransAm and he won't use anything but Mobil 1. Personally, I believe the owner should use whatever gives him the most peace of mind. At least for cars, for bikes most certainly diesel oil due to the fact that it also lubricates the transmission and can't use "energy conserving" additives for the reasons already posted.

[Nessism]

Synthetic oil is more temperature stable, thus a thinner base stock can be used to build a multi weight oil compared to mineral oil. For example, Rotella synthetic is 5W-40 (using 5W base stock) but the mineral variety is 15W-40 (using 15W base stock). I think it would be difficult (expensive) to build a 5W-40 mineral oil that met the same requirements as the 15W-40 variety.

Because the 5W base stock is thinner than 10W or 15W oil, it will exploit sealing voids more easily. Also, synthetic oils by virtue of their viscosity stability, can be run for an extended drain interval compared to mineral oil. Oil designers knowing that often include more acid buffers and detergent into the base oil to compensate. Extra detergent may loosen sludge plugging leak paths too.

As for synthetic oil reducing friction, I'm not so sure. I believe they do under high heat conditions, and during extended drain intervals. But I don't think they do much of anything to reduce friction other than they are often lower viscosity, which does reduce friction when the engine is cold because it flows better. Under normal running conditions I don't think synthetic will reduce friction compared to mineral oil all things being equal.