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#11 |
![]() Join Date: Jan 2012
Location: Wisconsin
Posts: 887
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#12 |
Join Date: Mar 2009
Location: Orlando, FL
Posts: 1,828
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I think I remember reading that 10-12,000 miles is about the maximum before the viscosity drops below a "safe" range.
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2004 Z06/Z16 LeMans Commemorative Edition 1991 ZR-1 #302 White/Gray (sold) 1991 ZR-1 #1147 Red/Saddle (sold) |
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#13 | |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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I put 12k miles on my Z in 4-1/2 seasons. So, I guess changing it "often" is a relative thing - depending on driving. Maybe Marc Hiabeck can chime in here on this change iterval too. If I recall, Marc has a different opinion regarding oil change itervals for the ZF, as well as an opinion on what to use in it. And, too... I recall where he tells of a guy in France that had his ZF freeze up on him while cruising in his 95 ZR-1. (That makes two 95s; his and mine that had that problem!). I guess my feelings on it is that at least some ZFs were/are prone to having inherent lubrication issues (to that reverse gear). So, because experimenting with different oils is practically beyond the ability of all but a tiny number of automotive engineering types, or emperical data gathered by those that repair them on a regular basis, I defer to the latter especially for input on what to use - and how often to change it. I am damn sure I don't want to have another ZF lock up on me for lack of the "right stuff" whatever that might be! And, there is no doubt there is more than one lube out there that will meet or exceed the ZF needs. Picture this: A crowed expressway, cruising at 70 mph. Suddenly the car is decellerating as tho I was braking rather firmly. No brake lights, mind you, and no shoulder on the left side of the expressway. Engine is lugging hard in 6th to maintain cruise control input. Gotta get off this damn expressway NOW! Down shifting to 4th and give it more throttle, trying to maintain position and signal a right lane change - but still decellerating! I squeeze in front of the car in the right lane next to me, and then practically cutting off the guy in the next lane over to finally get to an off-ramp, just as the rear end locks up and brings the car to a screaching halt!! OK, this is a rare occurance, to be sure. But, it is not unknown to this transmission, according to Bill B. And, it seems to be (from what others have said) more prevelant to 95 MY especially; including base model Vettes as well. So, I guess I'm trying to say that for me only, perhaps, I get a little nurvous about wandering off the path when it comes to lube recommendations in this application. There's more at stake than how it shifts...is my point, I guess. Everyone's mileage may vary, I recon. ![]() ![]() P.
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry |
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#14 | |
![]() Join Date: Jan 2009
Location: Portland Oregon metro area (Washington side)
Posts: 3,207
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I've rebuilt a few ZF6s and the only thing I saw about the reverse rail of concern was the entry point for oil. It's vulnerable in that if you're even a slight bit low on oil it's bad news for the rail. Opening up the groove I'm sure would help but...... not a fix all. I keep my ZF6 ever so slightly overfilled.( 1 cup) And I make very sure the ZF6 is sitting level when filling it. I also use the stock GM oil (or Havoline 10w30) Come to think of it, it's time to swap out the oil and coolant this year.
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Scott ![]() Vett owner since 1979._It's about the car and the people |
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#15 |
Join Date: May 2007
Location: Chicagoland, IL
Posts: 9,696
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I change my Castrol TWS about every 10,000mi. Have used it for ~ 10 years.
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[SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX |
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#16 | |
![]() Join Date: Dec 2003
Location: Arcadia,OK
Posts: 3,384
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I know of a 91 that it happened to also. Bill B. gave me the same explanation with a little discussion on lube. I drained the factory fill, which looked good, & replaced with Redline about3K miles before the failure. Bill said he's heard of 2 other failing after changing to Redline. I use the Castrol now. Having that failure on a multilane highway with traffic, like Paul, would be scary. Could easily happen in a traffic lane if you didn't react very quickly.
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
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#17 |
![]() Join Date: Oct 2004
Posts: 1,889
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In these instances of "lock-up" what internals of the transmissions were actually damaged and required replacement?
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