Midwest Vette

Anybody running synthetic oil in a ZF 6 speed. If so, which oil are you using?
Thanks Ron...... :flag

Zrxmax

Just filled my ZF with Castrol 10W 60 synthetic as recommended by some knowledgable types... Had to go the a BMW dealer to find it... got reamed for $15 a quart... should only have paid $9 a quart... Seems to work just fine... This is the same oil BMW recommends for their stick shift cars... the German connection at work here I guess...
Have also heard good reviews about redline synthetic...
All for now...
Ted

trrgod

I run the stock GM oil. If there is any advantage to running the synthetic it is minimal for normal use. I'm sure there are knowledgeable people who have opinions on what synthetics to use but they aren't going to help to pay for any repairs if the lubricant doesn't work correctly. I personally believe in the superior lubricating qualities of synthetic and use it exclusively in my engine. However, I too investigated the use of synthetic in the ZF and found that there were too many different opinions and not enough absolute knowledge so I opted to go with stock oil. I've never heard anywhere that a ZF trans broke under normal use because it had the stock oil in it.

C4396roadster

I have read in the forum maitenance not to use redline not the correct grade oil, I run amsoil which make the correct grade no problems whatsoever as with all of the amsoil products I have ever used, very slick and smooth operation upon use you will notice diff in synthetic oils off the bat

Nathan Plemons

I've heard everything from everybody on this one, nobody seems to have an agreeable opinion. Personally I go with the factory oil, it's still expensive at $8 a quart, but how can you go wrong with it? If you car should happen to still be under warranty you wouldn't put anything but the recommended fluid in it, so why would you do so when it's out of warranty.

HJV11

I agree that you will not find any kind of agreement on this subject. But for your info I have been running Mobil 1 in my ZF for 4 years now with no problems whatsoever.

LEADFOOT_

Ron

There are a lot of guys running different oils. Red Line happens to be the oil I choose because it was recommend to me by some ZR-1 friends and also the choice of DRM and Lingenfelter. I have been running Red Line MTL for a while; there is nothing wrong with running Synthetics. A lot of the ZR-1 guys I understand run the Red Line MTL also. I have heard no problems from anyone having failures except one guy running Synthetic oils.

EricVonHa

I just finished re-installing my ZF... Devon BMW charged me a hair over $11 per quart!!! OUCH!!!!

On another note, I had a mix of Mobil1 and Redline in the trans for the last clutch... tons of hard driving... the clutch lasted 20k miles or so and the fluid came out clean!

MarkBychowski

I also use the Castrol (BMW part num 07-51-0-009-420 ). It is the only synthetic I know of recommended by ZF for use with the ZF6. Trans shifts very smooth and it hold up very well to occasional road-race weekends.

A while ago, my local dealer put Mobil-1 in it (their recommendation). It was more difficult to shift and more noisy after it got heated up.

AquaMetallic94LT1

In a nutshell, the most common selections and issues with them are:

1. GM oil. No issues. Usually $8.00 per quart.
2. Castrol 10W60 synthetic. This is recommended by ZF and used by a lot of guys. Usually $8.00 per quart.
3. Redline MTL - Not recommended by either GM or ZF. Used and recommended by Lingenfelter and DRM. Also used by a lot of forum ZF owners. Usually $8.00 per quart.

I have Redline MTL. Be sure to change the fluid every 30K miles.

Valdez

Surprisingly, the Oil Preacher Rick93Z07 (Mr. Know-it-all) and his worshipping congregation PeteL haven’t jumped onto this oil topic yet. Make no mistake they will be here doing their preaching on the GM fluid. You would think those guys might be paid by GM the way they preach!

ROADRACER_

I'm running the Red Line MTL just like some of the other guys in which I’m very please with. Seems like this ZF fluid issue has been an on going battle between the different oils. I know a lot of guys running the Red Line MTL, which they absolutely love it, then there are other guys that won't have anything to do with it. It’s like chocolate or vanilla, take your pick.

Midwest Vette

Thank you all very much for the information.
Ron... :flag

Rick93Z07

Valdez,

Great post#1 buddy....flaming, criticizing and characterizing other's for posting (or not posting?) their opinion on an open forum. How about taking your namecalling elsewhere. If you have anything useful to offer about ZF lubricants in this thread I haven't seen it yet.

Although GM lubricant specification requirements are always clearly stated, I feel auto manufacturer's "mystery lubricants" are almost unethical because they endeavor to hold the "uneducated" consumer hostage. In 30 years, I have bought perhaps 10 quarts of GM lube. With respect to the ZF, "educated" consumers will NOT find an alternate API approved lubricant that meets minimum OEM requirements (viscosity and GL designation). For this reason, some (like me) feel it's safest to follow ZF and GM recommendations. I feel ZF is the most qualified to offer alternates and they only recommend two lubricants, as stated above. As a person with first hand engineering experience in lubricant research, development and testing, I have felt a need to share my concerns and opinion on this topic. (Valdez), please ignore my opinion if it bothers you.

Rick

1991Z07

I've run both the RedLine MTL and the Castrol for years (more than 6 now) with no issues. The one thing I immediately noticed was the shifting is smoother with the synthetics. There was also an average of a 35 degree drop in transmission temperature under light load (street driving) and almost a 100 degree drop in track driving.

I talked at length to the ZF engineers at a BMW service convention a few years back. They dug up the data and sent it to me about the Castrol oil. The only reason that GM didn't use the Castrol here was that it (the Castrol sythetic oil) wasn't used in the US, and Castrol had absolutely no plans to do so. The ZF6 was tested with the Castrol and GM's "so-called" OEM replacement, and these were the only two oils that ZF ever tested for durability.

I then spent a total of about 4.5 hours on the phone with some engineers at ZF in Germany asking the same questions those here on the forum ask every day. They informed me that the only two oils "officially" authorized for use in the ZF6 are the OEM fluid and the Castrol...any other oil would void the warranty.

For those that don't know much about synthetic oils and how they can extend the life of moving parts I'll impart a short story I heard from Dick Gulstrand a few years back.

Dick had at that time an early ZR1 that they had been using for testing and just general fun in their shop. Every 30k miles they would do a complete teardown of the engine and examine it for wear. After over 120k miles, they could still see the cross-hatches from the honing process in the cylinders, and the wear was zero-thousanths of an inch...after 120,000 miles. And guess what they use in the LT-5? You guessed it...sythetic oil (Mobil 1 to be exact).

As a further testament to how synthetic oils extend life for cars, I toured the Mercury Marine Plant where the LT-5's were assembled a few years back as well. They had an engine there on a stand that had run at Wide-Open-Throttle on the dyno over 20 HOURS before failure (which in this case happened to be an oil-pump failure). As a comparison, a "standard" V8 won't last over 3 hours on a dyno at WOT. Even after all that, the oil was still golden. They had camshafts sitting there with over 500,000 miles of "dyno miles" and they still looked brand new. They were still within the factory specs for a new part.

There are those who believe that the OEM fill is "the only" solution. If you don't push the car hard, it will do. But there will be wear on the moving parts inside the trans, which will eventually require you to do a complete rebuild of the transmission. Running synthetics will minimize the chances that this rebuild will hit you hard in the wallet.

Of course, this is a personal opinion. I don't have the engineering degree in the field to say this. But I do listen to those that do (have a degree). There has got to be a reason that synthetics are used in racing and many other forms of motorsports. Those guys don't just throw good money away "because they can". They put products into those cars that will get them to the end of a race. I'll use them in my cars....always. I'd put pure silicon fluid in the brakes if it would work with ABS.

I'll step off the pulpit now and let someone else take a shot. :chevy


[Modified by Joe90, 9:18 AM 11/26/2001]

Nathan Plemons

I'll just state it again after that lecture, you can't really go wrong with the OEM fluid. If ZF recommends the Castrol synthetic it is probably better, can't go wrong with the factory recommendation. Take what is recommended by the people who made it, it's just good sense.

On the motor oil, MOBIL 1. I will never run another oil, when I've had my engine apart for the cam, and when I had the oil pan off, etc, it's amazing how clean everything still is. There is no buildup on anything. One friend has a camaro that uses Mobil, his engine is the same story, somehow he spun a rod bearing (I think it's because he never runs an air filter, he won't admit that), the motor was still spotless, other than the metalic flake in his oil.

Another friend has the same year camaro, close in mileage. The previous owner didn't run mobil. We pulled a valve cover and were scared by what we saw. Everything was caked in black sludge, we put the valve cover back on, hoping we didn't see what we thought we did :( He's looking for a rebuild now.


[Modified by Nathan Plemons, 9:41 AM 11/26/2001]

LT4Abe

I was wondering what, switching to a synthetic oil does to your gaskets? Do you have to change to a gasket that is intended to be used with synthetic? And if so, is that all you have to worry about changing on a car with miles on it. Over 50K for example.

Corvette ED

Synthetics have a good cleaning properties.

As for the ZF debate My guess is that GM being the cheapskates that they are didn't want to spend a few bucks more and put the Castrol in. Anywhere to save a buck they will skimp.

I have used Redline MTL without any problems and as stated above it does make the transmission shift smoother and have less noise.

365ZUM

Nicely done, Joe.

VMAX451

Strange, but it's really Texaco (Havoline) 5w-30 motor oil, repackaged for GM. Talk about a price mark up! But of course motor oil formulations change all the time so it may still be the '90 formula, who knows. I'd just get the GM stuff and not worry about it. Still cheap at $8/qt when you think of how much you need.