Synthetic or Petroleum Based Gear Lube In The Trans? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69 1/2 Sixpack Bee · 04-23-2004, 12:07 PM

Which would YOU put in your granny-gear 4 speed?
I have the Valvoline synthetic in my '72 right now and I am not sure but it seems to shift a little harder than before. Should I go back to the 85-90?
Thanx

69sixpackbee · 05-06-2004, 06:24 PM

back up again

Cethern · 05-06-2004, 06:52 PM

For me it's Synthetic all the way. I don't think you can beat Synthetic oil. Now if you think the tranny is shifting harder there could be something wrong in the tranny, I don't see how a good synthetic oil could do that.

Cethern

Longhorn Man · 05-06-2004, 07:06 PM

Keep the good oil in there...you didn't use a lightweight oil did you?

69sixpackbee · 05-06-2004, 07:12 PM

Nope, Valvoline 85-140

crazy longhorn · 05-06-2004, 07:14 PM

I am running Redline synthetic in in my Richmond box(by richmonds reccomendation). the thing you have to watch , is that there is no friction modifiers in the lube(for positrac use). this can cause problems with the syncro blocker rings running too "slick". According to richmond, there are not too many synthetic gear lubes that dont have the positrac addative on the market anymore. i can get a # on the redline lube if you like.....just need to step out to the garage. crazyL

Got it, 75W90NS Redline synthetic. For use in manual transmissions,trans axles, & special rear drive racing diffs. This was the stuff that Richmond reccomended for drag strip use in their $3000 gearbox.....yea, my wallet still hurts on that one, but it shifts slick as hell, & is lots of fun to drive

there was another synthetic i tryed from Orielys that was a 75/140.....it worked ok, but shifted a little stiffer. Good luck,crazyL

Hooter · 05-07-2004, 12:55 AM

I had synthetic in my 3 /12 speed tranny and it shifted nicely, now I put regular oil into it and its really stiff to shift, so I would reccomend synthetic

Bowtie67 · 05-07-2004, 07:26 AM

Here is a little trick I used to use that I learned from an old buck, doesn't matter what manual trans you have. I used to use it on my harley 4speeds then started using it in customers 5speed jeeps that use to have real hard time shifting. I used to use BG engine concentrate, something like STP, put about 1/2 cup or about half the container in the trans and it will shift like cutting warm butter. I have had a lot of customers compliment me after having to rebuild their trans because of broken forks from trying to get it in gear and on how easily it shifted afterwards and that it had never shifted so nicely. I've used on many different transmissions.

sbc350gearhead · 05-07-2004, 08:59 AM

I like RP and redline gear oils. As far as redline goes........MTL, MT-90 and 75w90NS are all designed for manual tranny applications. IIRC the 75w90NS is a GL-5 fluid, so you must not use it in appications that spec a GL-4, for most GL-5 fluids are corrosive to soft yellow metals. All three of the aforementioned fluids have different viscosities and will give different shift feel, so experimentation is recommended. The MTL and MT-90 can be mixed to give a specific shift feel. RP max-gear 75w90 is GL-4/GL-5 rated fluid so it is safe for soft metals.

imdarren · 05-07-2004, 09:29 AM

Nobody has mentioned it yet so I will . . . . .
The only caution about synthetic in old vehicles is that if the gearbox, rearend, pwer steering pump, motor etc is old, the seals may start to leak when you put in synthetic. It does such a good job cleaning up the old seals etc. stuff often starts to leak. I know this from experience (the hard way). If it is a new motor, trans, gearbox, etc. then it is a diffrent story. but a 30+ year old unit? Be warned.

Just my .02

Darren

Longhorn Man · 05-07-2004, 11:20 PM

While I have read that over and over, I have chainged over will over 100 engines of variouse mileage to synthetic...my wife's 70K contour, all the way to our 92 F-150 with 227K and all original unopened engine....none have ever come back with a new leak.
Not saying it isn't true, see too many ppl claim it to be true...just reporting my observations.

jeepbut · 05-07-2004, 11:55 PM

I agree with Andy-never had synthetic stop or start a leak.

Huck · 05-08-2004, 08:13 AM

A local trans shop owner with like 40 years in the business uses Mobil 1 TRANS fluid in his personal vehicles and swears by it. I had a 97 C5 Corvette with a 6 speed that was notorous for occasional shift failures-not speed shifting but going into 1st gear from neutral -would give you the feel of the detent but not actually getting into the gear. He suggested Mobil 1. Within a 1/4 mile from my install, the gearbox felt different and didn't fail once in the next 10K miles where it would about every 20 miles before. I sold it without one failure after the Mobil 1 swap.

04-23-2004, 12:07 PM	#1
69 1/2 Sixpack Bee Registered User Join Date: Mar 2000 Location: Ontario, California Posts: 40	Synthetic or Petroleum Based Gear Lube In The Trans? Which would YOU put in your granny-gear 4 speed? I have the Valvoline synthetic in my '72 right now and I am not sure but it seems to shift a little harder than before. Should I go back to the 85-90? Thanx

05-06-2004, 06:52 PM	#3
Cethern What was I thinking?? Join Date: Dec 2003 Location: Commerce City Co Posts: 637	Synthetic For me it's Synthetic all the way. I don't think you can beat Synthetic oil. Now if you think the tranny is shifting harder there could be something wrong in the tranny, I don't see how a good synthetic oil could do that. Cethern __________________ 72 K5 that needs lots of parts.. 71 GMC 3/4 4x4 That doesn't need much which is a good thing I don't think I could aford another money pit...

05-06-2004, 07:14 PM	#6
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	I am running Redline synthetic in in my Richmond box(by richmonds reccomendation). the thing you have to watch , is that there is no friction modifiers in the lube(for positrac use). this can cause problems with the syncro blocker rings running too "slick". According to richmond, there are not too many synthetic gear lubes that dont have the positrac addative on the market anymore. i can get a # on the redline lube if you like.....just need to step out to the garage. crazyL Got it, 75W90NS Redline synthetic. For use in manual transmissions,trans axles, & special rear drive racing diffs. This was the stuff that Richmond reccomended for drag strip use in their $3000 gearbox.....yea, my wallet still hurts on that one, but it shifts slick as hell, & is lots of fun to drive there was another synthetic i tryed from Orielys that was a 75/140.....it worked ok, but shifted a little stiffer. Good luck,crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... Last edited by crazy longhorn; 05-06-2004 at 07:36 PM.

05-07-2004, 12:55 AM	#7
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	I had synthetic in my 3 /12 speed tranny and it shifted nicely, now I put regular oil into it and its really stiff to shift, so I would reccomend synthetic __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

05-07-2004, 07:26 AM	#8
Bowtie67 Registered User Join Date: Jan 2004 Location: NH Posts: 2,266	Here is a little trick I used to use that I learned from an old buck, doesn't matter what manual trans you have. I used to use it on my harley 4speeds then started using it in customers 5speed jeeps that use to have real hard time shifting. I used to use BG engine concentrate, something like STP, put about 1/2 cup or about half the container in the trans and it will shift like cutting warm butter. I have had a lot of customers compliment me after having to rebuild their trans because of broken forks from trying to get it in gear and on how easily it shifted afterwards and that it had never shifted so nicely. I've used on many different transmissions. __________________ 1967 C10 - SWBSS Pro Street 427sbc, 700R4 & 4.10 Gears 1948 Chevy FleetMaster Coupe, LS1, (almost done) 1950 Chevy StyleLine Coupe 250/6 3x2 Dueces 2009 Toyota Tundra 1996 Harley RoadKing "I maybe getting old, but I can still burn rubber with the best of them"

05-06-2004, 06:24 PM	#2
69sixpackbee Registered User Join Date: Jan 2001 Location: Sabinal, Texas Posts: 1,706	back up again

05-06-2004, 07:06 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Keep the good oil in there...you didn't use a lightweight oil did you?

05-06-2004, 07:12 PM	#5
69sixpackbee Registered User Join Date: Jan 2001 Location: Sabinal, Texas Posts: 1,706	Nope, Valvoline 85-140

05-07-2004, 08:59 AM	#9
sbc350gearhead Registered User Join Date: Mar 2003 Location: Columbus Ohio Posts: 1,413	I like RP and redline gear oils. As far as redline goes........MTL, MT-90 and 75w90NS are all designed for manual tranny applications. IIRC the 75w90NS is a GL-5 fluid, so you must not use it in appications that spec a GL-4, for most GL-5 fluids are corrosive to soft yellow metals. All three of the aforementioned fluids have different viscosities and will give different shift feel, so experimentation is recommended. The MTL and MT-90 can be mixed to give a specific shift feel. RP max-gear 75w90 is GL-4/GL-5 rated fluid so it is safe for soft metals.

05-07-2004, 09:29 AM	#10
imdarren Registered User Join Date: Oct 2001 Location: SW Washington Posts: 1,006	Nobody has mentioned it yet so I will . . . . . The only caution about synthetic in old vehicles is that if the gearbox, rearend, pwer steering pump, motor etc is old, the seals may start to leak when you put in synthetic. It does such a good job cleaning up the old seals etc. stuff often starts to leak. I know this from experience (the hard way). If it is a new motor, trans, gearbox, etc. then it is a diffrent story. but a 30+ year old unit? Be warned. Just my .02 Darren __________________ Washington State 1967 Chevy C10 LWB Rodstoration In Progress. 1972 K20 Cheyenne Super

05-07-2004, 11:20 PM	#11
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	While I have read that over and over, I have chainged over will over 100 engines of variouse mileage to synthetic...my wife's 70K contour, all the way to our 92 F-150 with 227K and all original unopened engine....none have ever come back with a new leak. Not saying it isn't true, see too many ppl claim it to be true...just reporting my observations.

05-07-2004, 11:55 PM	#12
jeepbut Registered User Join Date: May 2001 Location: Corpus Christi, Tx. U.S.A. Posts: 271	I agree with Andy-never had synthetic stop or start a leak.

05-08-2004, 08:13 AM	#13
Huck Senior Member Join Date: Jun 2001 Location: Shelbyville, KY Posts: 3,269	A local trans shop owner with like 40 years in the business uses Mobil 1 TRANS fluid in his personal vehicles and swears by it. I had a 97 C5 Corvette with a 6 speed that was notorous for occasional shift failures-not speed shifting but going into 1st gear from neutral -would give you the feel of the detent but not actually getting into the gear. He suggested Mobil 1. Within a 1/4 mile from my install, the gearbox felt different and didn't fail once in the next 10K miles where it would about every 20 miles before. I sold it without one failure after the Mobil 1 swap.



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