Do you use synthetic oil?

[Daox]

Do you use synthetic oil?

If so, where do you use it (engine, trans, or both)?

If you don't, why not?

[i_am_socket]

I just switched over at my last oil change. I figure since I usually go 6-12 thousand miles between oil changes, I probably should just to keep the car running.

[IndyIan]

I'm doing mostly synthetic engine oil now, I'm autocrossing the Neon so it sees the fuel cut off once in a while (6800rpm), and the tracker is known to have timing chain tensioner issues that I think comes from oil sludge build up. Synthetic oil generally sludges up less.
I am going to start changing the oil filter at 5,000km and then the oil and filter at 10,000km. I change my own oil and can get synthetic on sale for $20so it doesn't cost anything extra unlike the lube places. A change with synthetic would run $60 here...
Ian

[metroschultz]

I just got a newer engine and I want it to last as long as possible.
I use synthetic everywhere I can.
I believe in the power of synthetics and by increasing the time between changes I reduce the amount of waste oil I produce.
I am up to 10K between changes in Barbs car and the oil I remove is almost as clean as th oil I put back in. I do, however, change the filter @ 5K and top off the oil. This makes me feel better and it may or may not have an actual effect on the longevity of her motor.
S.

[PaleMelanesian]

Synth in the engine. The trans will get synth when it's due, but not before then. The minivan will be getting synth soon, as well.

[Red]

I run synth in everything, engine, diff, trans, t-case.....

[johnmyster]

I've never been convinced that synthetics are any better. Castrol GTX is my fave. Pensoil, Valvoline, or whatever is on sale.

On a given oil change, half of my driving will be long (400 mile) highway trips. The other half will be 2-3 mile trips to the store. I don't commute by car. Thus, I'm changing my oil more often to get the "short trip residue" out of my crankcase. The promise of long life oil wouldn't be a good idea for me.

I will, however, spend money on a better filter. Years ago, FRAM won acclaims for their filtration. However, I think their quality has gone down. The nicer FRAMs, Toyota, Mobil, Bosch , and Motorcraft (Ford) filters get my approval along with some others. I always open the box, and look for a "reverse flow seal" that is made of softer (red) rubber and a non-stamped top plate. The stamped plates always have buggers on the back of the holes that keep them from sealing well. I consider these backflow preventers to be critical in getting oil to your lifters and valvetrain quickly during startup. They help to prevent "drainback" when the engine is shut down. I like the grippy on the frams, but will only use their silver filter. Since I have a GM, that usually leaves me using Bosch, Silver Fram, or Mobil. Always liked the Motorcraft when I was a ford guy...

If you open the boxes in the store, you'll quickly see that it looks like only one or two companies out there make filters...

80/90 wt is my fave for differentials, though it smells like dinosaur poop. A lighter oil seems to be better for manual trannies - easier on the synchros. GM reccomends their own blend, and pensoil is the only company that makes it - at $6.50 a quart it may as well be synthetic. I'd rather change ATF more often than run synthetic and pretend it lasts any longer.

[PaleMelanesian]

Here's a study: http://me.engin.umich.edu/autolab/Pu...e/P2002_03.PDF

On page 10, there's this chart:

[johnmyster]

Originally Posted by PaleMelanesian

Here's a study: http://me.engin.umich.edu/autolab/Pu...e/P2002_03.PDF

That's a joke, right? Two data points show a conclusive trend?

Look at figure 12. You'd expect heavier oil to be more "inefficient." Those three data points show no trend at all.

Further, text right next to figure thirteen - "This was the only regime in which the full synthetic was found to outperform the mineral oil."

The only conclusions of this paper are that for this engine - there's no statistically substantial claims to be made for any oil of the 12 tested. This was primary an emissions study, conducted at one set of operating parameters on one engine. Not a fuel consumption study on multiple engines or a range of operating conditions. Not an engine wear study on multiple engines over broad operating conditions. It was primarily a friction modifier study - and using different types and grades of oils was a way to incorporate this.

Consumer reports did a study years ago using NYC taxis. 100s of thousands of miles on motors using one oil vs another. Huge population sizes of engines (same engine, same car) measured before and after service...that was a wear study.

[PaleMelanesian]

Originally Posted by johnmyster

Consumer reports did a study years ago using NYC taxis. 100s of thousands of miles on motors using one oil vs another. Huge population sizes of engines (same engine, same car) measured before and after service...that was a wear study.

And the conclusion was...