ZF 6 oil

[secondchance]

I know this subject has been beat to death. One simple question - what was the factory fill? Any particular reason we debate between Castrol and Redline? I must have missed something.

[WydGlydJim]

I'm running the Amsoil stuff......seems to shift well so far. GM part #1052931 is under the list this fluid replaces.......website says you can go 50,000 miles between changes.........


http://www.amsoil.com/storefront/mtf.aspx

[ZR1Vette]

I use Amsoil AMO for the engine and Amsoil 75W-90 Severe Gear+ Amsoil Slip Loc additive for diff and Castrol TWS for the tranny.

[tomtom72]

Cliff, long story longer.... My car I got from the O.O., 7400 miles / 14.5 yrs old. Everything in the car was OE/BG save the motor oil & coolant ( thank god! this guy was questioning the use of synthetic motor oil in a 90 Z!!!!! ).

I used to use the GM replacement fills for the gear & trans, until one session I had time on my hands and I was comparing P/N's in the owner's manual to the stuff I just bought at the local chevy dealer ( after I had put the stuff in both! I know I'm sooooo very perceptive! ). I nearly choked when I saw that the gear lube was not spec'ed to the exact specs as the OE/BG stuff that came in the car. I figured who cares as I change it every year anyway, same with the trans fluid from GM. I asked at the dealer about the two fluids and read up here & at Bill's site.

Result: I stuck with the GM gear fluid + two bottles of additive ( as per Gordon's instructions ) because the chevy parts guy said it was the same GL # but that the additive pkg was tailored to the 5's & 6's. The trans stuff he couldn't give me a GL # on for either what came in the car from BG or what the new stuff was from GM. He said I was on my own on that call.

I got caught up in the "bad, poorly made" clutch hydraulic parts a few yrs back that GM had on the market. I changed six sets, yes six sets, of M/C's + slaves in my car in the span of six months. That's when I decided to go with the BMW oil exclusively for the box and ditch the newer GM stuff. I was switching out the box oil every time I had a hydraulic failure because no one picked up on GM quality control problems. I didn't know what was causing my box to make the grinding noises till Bill doped the issue out & told all of us.

The last gear oil I just switched last winter to the sever duty amsoil fluid + one additive(theirs) and it went 5,036 miles without a hick-up....but that is going to be changed as it's part of my "winter get ready schedule". I will proly go with something I can get local, maybe M1 stuff or back to GM for their stuff. I hate to say this, I'm less worried about the gear lube than the box fluid. The gear lube is GL5(?) by the specs for a C4 ( I maybe wrong on that ), but my point is that the correct GL # lube for the gear is easily obtained almost anywhere. The box's correct GL # lube seems to me to be impossible to find for sure. Therefore, I'm OCD about the gear box lube changes as ( hopefully ) a precaution to forestall syncro failure.

btw, I know that on this subject I'm out where the buses don't run. In terms of my "maintenance schedule", some people could use the stuff I throw out every winter! Any one wanna buy a set of correct date coded 1990 FR2LS spark plugs?

[Aurora40]

Originally Posted by secondchance

I know this subject has been beat to death. One simple question - what was the factory fill?

I believe the factory fill was a motor oil made by Texaco that had the correct properties GM was looking for. It stopped being produced about 10 years ago. The fluid GM sells now is not the same stuff as the original fill.

This is why it is debated as to what the "best" fill now is.

[ZR1Vette]

Was the ZF tranny made in Germany by ZF Getriebe GmbH in Saarbruken, Germany? Or did ZF have a manufacturing facility in the US (as it does now)?


If the answer to the first question is 'yes' then probably the "factory fill" would have been Castrol 10W-60

[secondchance]

I am not too crazy about changing fluids every year (10 - 12,000 miles) if I can avoid it.
I have 110,000 miles and perhaps changed it once at around 40,000 miles or so with no issue.
Am I taking too much risk? I was thinking if I stayed w/ factory fill, perhaps I could avoid anual change.

Your thoughts, guys?

[Dynomite]

Originally Posted by secondchance

I am not too crazy about changing fluids every year (10 - 12,000 miles) if I can avoid it.
I have 110,000 miles and perhaps changed it once at around 40,000 miles or so with no issue.
Am I taking too much risk? I was thinking if I stayed w/ factory fill, perhaps I could avoid anual change.

Your thoughts, guys?

I think you are with majority

I prolly change transmission and differential oil every 50,000 miles on some vehicles....longer change interval on most vehicles.

But then again...the Z gets special treatment......and I will prolly change transmission and differential oil every 15,000 miles more or less on the Z. I did add the drain plug in the differential to make changing oil a lot easier on the 91' Z

I use castrol TWS 10W-60 (transmission), Mobile 1 75W-90 (Differential) and Amsoil 10W-40 (Engine).

[secondchance]

I guess I will stay with factory fill.
10-12000 miles change for BMW Castrol comment concerns me.

[Dynomite]

Originally Posted by secondchance

I guess I will stay with factory fill.
10-12000 miles change for BMW Castrol comment concerns me.

I think the issue of suspended spent synchronizer material is associated with any transmission oil you might use (more so with GL-5 than GL-4 lubricants because of the additives - see below)

Not necessarily associated only with (I think even less associated with - see below) the use of Castrol TWS 10W-60

The recommended oil change interval of 12,000 miles by Bill B. will reduce the accumulation of that suspension of synchronizer material which may be more significant an issue with the ZF S6-40 6-speed transmission.

Some bits of additional information by others

"Some late model Corvette transmissions (ZF) have a reputation for generating significant quantities of bronze particulate mud and require both special synthetic lubricant and frequent changes to achieve old age. At one point a few years ago I think there was just one lube in the world (maybe by Castrol) that was ZF approved."

"API GL-4 and API GL-5 products typically use the same extreme pressure (EP) additive system, with the API GL-5 having about twice the concentration of EP additive as API GL-4. In service, these additives become active under extreme load and temperature when the protective oil film can be squeezed away. EP additives work by forming wear-resistant compounds with the metal of the gear tooth surface. As the gears mesh, these compounds shield the gear teeth from direct metal-to-metal contact that would cause wear and damage to the gears. If too little of the active additive is present, proper protection would be compromised. Too much of this EP additive could cause excessive chemical corrosion of the gear surface.

If an API GL-5 gear oil is used in a application where API GL-4 gear oil is called for, chemical corrosion of "yellow metal" components may occur, such as bronze synchronizers, brass bushings, etc. This may lead to shifting difficulties or shortened equipment life."