I went to Falore Nissan in Sunnyvale yesterday for my first oil change. I asked for Syntheitc oil and they had Castrol or Mobil 1. I chose Mobil 1. No comments regarding any problems with it.

 

Why the recommendation against synthetics in the trans & diff? Redline has always done fine by me -- what will it screw up?

Thankx. J

 

Well, it's not good for the diff if you have a limited slip; on account that it's supposed to use that viscous-snot stuff. Maybe the same for automatics since they have clutch packs immersed in the oil...but then again I've always used Amsoil in my Ninja and never had problems. As soon as I get 12,000mi on the Z, she's getting Amsoil too!

Synthetics rock, but they're very thin: I've had oil leaks in everything that I've changed over to synthetic. A small price to pay for the huge advantages they have over dinosaur juice. Synthetics don't break down in gasoline or water, and don't contain any wax to clog things up.

 

I have been using synthetics for over 10 years now and would not use anything else. They have come a long way during that time, too!! I have never experienced any leaks- even in engines that used dino oil for the first 40,000 miles before they were switched. I have had synthetic do an outstanding job keeping the engine operating during a cooling system failure one time- after that, I would never use conventional again!

I moved my rear diff and MT over to AMSOil Series 2000 gear lube at 4100 miles and am glad I did. There was a metallic, sludgy buildup around the magnetic plug in the diff in both my Z and a friend's.
The Series 2000 gear lube is rated for limited slip performance without any special additives. No need to mix 2 types of fluids as with Redline.
Supposedly it gives 4.83% increase in mpg- not sure I can verify that yet!!
It's bright blue color leaves no doubt that it is synthetic!!!

 

I just dropped by my dealership and scheduled a minor detail and an oil and filter change. I asked David, a new service writer to me, if they stocked synthetic oil and he said they used a GM oil compatible w/Japanese engines(Cadillac,Olds,Nissan dealer). I told him I wanted to go to a synthetic like Mobile 1 5W-30 and change at 5000 miles or every 6 months because I am driving more metro miles than highway and he didn't bat an eye. He said he would of course deduct the cost of the oil from my bill and I told him I wanted him to document on my work order that I was using a API Certified oil which meets all requirements for Nissan engines. No muss, no fuss and after reading the API CERTIFICATIONS it meets, makes the SM's remarks even more outrageous.

 

Do a search. There was a thread (at least one) where some people who race 350Zs had discovered some damage because of diff or tranny synth oil.

Basically, from what I remember, it was too thin and slippery and didn't allow the expected amount of friction to do the limited slip and/or to turn the synchros. Supposedly Nissan specified very specifically what you're supposed to use in those cases on purpose. More specifically than the engine oil.

 

I can tell you that the consistency of the AMSOil gear lube was no different than some conventional gear lube of the same weight that I had. Clearly, the synthetic will not suffer from thickening at very low temps like conventional lubes.
For racing, they do make a 75W-140 and if I was subjecting my Z to that type of use, I might consider that weight.

The transmission is definitely shifting much easier.

 

I picked up my car today after having it changed over to Mobile 1. The same thing happened again that has happened on my last 4 cars when I changed from mineral oil to a synthetic. The car idles smoother, the power seems to be slightly increased and the "feel" of the engine was enhanced. Some may think this is a delusional, but I don't think it is. Case in point, if I felt it in 1 car, I could buy the delusion theory, but the same in 5 cars, no way am I delusional about the changeover! Its pretty simple, IMO, the weather has hit Summer here and it is HOT! 95-96 degrees and no clouds to shade from the sun. The Z was taking it in stride but the power was down some, normal stuff in the heat. Everyone knows synthetic oil flows better in hot weather than conventional oil, it has been demonstrated in countless tests and it showed up today in my Z after the changeover. The engine runs cooler and smoother with synthetic than conventional oil.

I don't argue about breakin or all that because of all the performance cars that come from the factory w/synthetic, you read the list earlier. I will admit the 60,000 mile changeover may be too much, because I did experience oil consumption in my 91 MR2 Turbo. I changed over to Mobile 1 at 80,000 miles, but when I traded it in at 128,000 miles, it was using only about a quart every 1200 miles! I was still taking it to redline at 7300 RPM every day, w/the original turbo, including the day I traded it. Tough car, good oil, you be the judge.

Boomer babble

 

Actually, it's exactly the opposite. Synthetic oil flows much better than conventional oil when it's cold (especially very cold, like a cold engine in the dead of winter).

Hot oil flows freely. But synth is still considered "slippier", and it has much better resistance to breakdown at extremely hot temperatures.

 

Pardon me, I should have researched the differences between "flow" and "slippery" before making such a sweeping statement. Thanks for pointing it out.

 

Well you don't have to get snotty about it, because you were wrong. Synth flows well at low temps. Regular oil does not; it thickens much more. All oil flows well at high temps. Synth's advantage there is higher resistance to break-down.

Flow and the ability to coat and protect moving metal surfaces are not the same thing. Hence the "slippier" comment.

 

Both synthetic and mineral oil flow and coat metal surfaces. Synthetic does a better job of it. Your comment was an academic exercise and "slippier" isn't a word. You have not increased my or others' knowledge with your comments. As for snotty, your observation was not needed as a response to my post and I was NOT wrong, merely imprecise. There is a difference, BUB.

 

I have been told by the dealer that Senthetic is the way to go. I am now running with Mobile 1 in my Black Track.

 

My two cents worth on synthetics. Synthetic oil is superior to petroleum oil mostly due to viscosity breakdown. No jet engine uses petroleum oil because of the high operating temperatures. They only operate on synthetic oil. Petroleum would not hold up under these extreme operating temperature ranges. (Internal jet engine temperature ~1500°C while operating in minus 70°C outside air temperature at altitude). Granted this is not the same stuff that you buy at AutoZone but it is not petroleum oil either.

Synthetic oil adheres and bonds to metal. It does not slide off like the petroleum oils. This is a huge advantage during starting in cold temperature. Your engine, tranny, and diff are lubricated before you get into your car.

The two main reasons that the seals leak with synthetic: 1) in older engines, it cleans the deposits off and the worn or aged seals and they begin to leak [previously posted] 2) certain oil additives are corrosive in nature to rubber seals and O-rings.

If the oil is API approved, it meets the testing and warrantee requirements of the automotive manufacturers who use rubber seals and O-rings. Most manufacturers would not use the more expensive synthetic seals because of the higher costs. Therefore the API test requires compatibility with rubber seals.

Bottom line... the manufacturers do not want you to use a superior lubricant because your parts will wear very little or not at all and they won't be able to sell you new parts. Leaking has nothing to due with being too slippery or too thin. Sorry, my BS meter was pegging out.

 

1. So do the dealers have synthetics or would you have to suply it?

2. Do any of those teflon additives still exist? I used to run those in my old SI's

3. I've been changing my oil every 4K. Do you think thats to long to wait?

Thanks for your opinions.

 

Synth Royal Purple

I have been served the same crap about my warranty being void... changed dealer, everything is fine now.

 

The Service dept. Mgr at the local Nissan dealership here, who has been servicing my vehicles since he had his own shop years ago told me that synth oil gives off different fumes than regular oil and that the fumes that are being pumped back into your engine are not good for it in any way shape or form.
He said he wouldn't run synth in his Z if someone paid him to do it.
No flames please, I'm just repeating what he's been telling me since before and after he was with Nissan.

 

The Head Foreman at my Nissan says not to use synthetic. In the past two days I've met two people that have called him a genius. One of them has had him service all 5 of her previous Z's

 

Thats a good one. I have never heard of that before and hope never to hear it again. Its one of the least informed excuses to not use syn oil I've ever heard. Most manufacturers I have read about their stance on syn oil is to not change to it after 60,000 miles because it can seep past the engine seals. There's no downside if you keep to that interval. Syn oil is better, check the prices before you let a dealer put theirs in, I have always bought Mobile 1 or Castrol Full Syn and had the dealer put it in with the factory filter at every change.

My Honda dealer sold Castrol syn, but wanted $10 a qt., I bought and brought my own at $4 a qt. and not a peep did I hear. If they had charged $5 or 6, my time is more valuable than the difference. An extra $30 for 5 qts. is more markup than I will pay, period.

 

Like I said..I was just quoting. Personally I've always run Castrol GTX 10W30 in our climate and I'm happy and so is my ride