Tranny and rear end oil type?

Bo Mows · 03-04-2006

What is the preferred brand and weight of manual 4 speed tranny and rear end oil used in the GT? Just drained both in mine after sitting for 10 years (at least).

Bo

spdkilz02 · 03-04-2006

i used regular 80 weight gear oil...

asdasc · 03-04-2006

Just out of curiosity, how did you drain the diff? Did you just pull the cover and let it fly? I was looking at mine today and didn't see a drain plug. I must admit, I didn't look REAL hard, but I was thinking about doing what you are.

Bo Mows · 03-04-2006

Yep, just dropped the cover and cleaned it out and cleaned the cover and put it back on. I didn't even look for a plug. When the cover came off, it just kinda oozed out.

The tranny oil was really new looking. I think the PO did it when he rebuilt the motor.

80 weight in both?

Bo

spdkilz02 · 03-04-2006

yeah its just regular gear oil...

duaneb · 03-04-2006

FSM for my 73 GT list 80 or 90 wt in both

Bo Mows · 03-04-2006

Any comments on Lucas Gear Oil? I really like the Lucas motor oil in my 190,000 + Dodge Ram 318. Never used the gear oil though.

Bo

hrcollinsjr · 03-04-2006

One of the bottom bolts in the diff. cover will is supposed to drain the gear oil.

I put heavy weight gear oil in my tranny years ago. It worked fine until the outside temps started dropping. I got tired of having to force it into gear until it got to a decent operating temperature.

Harold

opelnut10 · 03-04-2006

80W is fine, I also get a quart of MOROSO high performance lube and put half in the transmission and half in the rear end. It may not help but it don't hurt a thing, it can stand high temps. better than regular gear lube. If you take the top and bottom bolt outta the rear cover after running it up on jack stands it will drain out and not make a big mess. Nothing smells as bad to me as used gear lube and if you get it on you it has to wear off

. After you let it drain take the cover off and clean it and fill with lube till you can stick your pinky in the fill hole and bend it at the first joint and touch the lube, just right then. Transmission has a magnet in the bottom of it's pan check it and clean the debre off and fill with the same method as the rear end.

opelwasp · 03-04-2006

I always use syntheticgear oil. Royal Purple, Red Line, Castrol Syntec, Mobil, all make synthetics. I run it in my engine after break in, trannys auto and stick, and diffs.

Bo Mows · 03-04-2006

I wondered about using Mobil 1. I have 2 commercial mowers (hense the name Bo Mows) and both use Mobil 1. As gear oil in my 36" walk behind and hydro oil in the 52" Zero turn mower. Will it effect anything if i used it in the tranny and rear without contamination from the previous lube in the GT?

Bo

layed521 · 03-05-2006

I have been sold on Lucas gear oils & oil additives. I see & hear the difference everytime I put it in 1 of the vehicles that comes into my shop. I have Lucas 80/90 in my diff & trans.

baz · 03-05-2006

bo mobil 1 will not be good as it will not work right as a gear oil
you need a hypoid gear oil
old axles ,old technology ,old type oil

fully synthetic oil will kill the seals quick time and put your axle in the junk heep when it brakes down and dont lubricate the gears

soybean · 03-05-2006

Originally Posted by layed521

I have been sold on Lucas gear oils & oil additives. I see & hear the difference everytime I put it in 1 of the vehicles that comes into my shop. I have Lucas 80/90 in my diff & trans.

I have to agree with layed521, I use Lucas gear oils & oil additives in almost all my farm machinery, with the exception of my John Derres' transmission. Since it is a synchro shift, it requires a special oil.
Jarrell

2 Fast 4 U · 03-05-2006

To drain the oil of the dif you have to remove the bottom bolt of the cover and leave it open for a while

RallyBob · 03-05-2006

Can't really go wrong with Amsoil or Redline synthetics. Less friction and better bearing protection is good. If you decide on synthetics, make sure you get gear oil specifically for a manual transmission...the rear axle gear oil is too slippery and will make it tough for the synchros to engage. Redline sells something called 'MTL' (manual transmission lube) which I swear by for Opels.

If you swap out the tranny lube, rear axle lube, front wheel bearing grease and engine oil for synthetics, expect 1-1.5 mpg better mileage and a few mph better top speed. It even makes the car easier to push...

2 Fast 4 U · 03-05-2006

Originally Posted by RallyBob

It even makes the car easier to push...

Do you have a car to push?? and that's why you put in that special oil??

Matt M240Z · 03-16-2006

How much oil does the 4-speed transmission take on the GT? Also, how do you fill it up? I am changing the transmission fluid for the first time by myself.

kent · 03-16-2006

what size are the trany pan bolts ? I lost and need all new

RallyBob · 03-16-2006

The FSM lists capacity as 2.5 pints, using either 80 weight or 80W-90 weight gear oil.

There are ten (10) bolts holding the oil pan to the transmission case. The thread pitch is 6 mm x 1.00. I don't have any bolts on-hand, but the depth of thread engagement into the transmission case is only about 10 mm. Add the gasket thickness and oil pan thickness to this number, and that's the max length bolt you can use. So probably no more than 12 mm long.

Matt M240Z · 03-17-2006

Do you take the oil pan off and fill it up with 2.5 pints and bolt it back on to fill the transmission? I just need to know if that is all that is required before I go to get oil and get the car up in the air. Thanks

baz · 03-17-2006

Originally Posted by Matt M240Z

Do you take the oil pan off and fill it up with 2.5 pints and bolt it back on to fill the transmission? I just need to know if that is all that is required before I go to get oil and get the car up in the air. Thanks

its been a long time since i played with one of these boxes but i think theres a drain plug in the base plate and theres a filler plug on the side that has a square head (dont quote me on this

) and you fill the box back up till the oil just runs back out of this hole then refit the plug

Matt M240Z · 03-17-2006

Ok, just got back from Napa with a quart of SAE 75W-90 gear oil. On the back, it says "recommended for all hypoid differentials (conventional and limited slip) and manual transmissions where an API GL-5 or MT-1 fluid is specified". This should work right? And is 2.5 pints really all the transmission needs? Thanks again

asdasc · 03-17-2006

If I remember right, you refill the trans thru the shift boot. Pull the center console, push the shift boot over to the side, reach your hand in the hole and there is a twist off cover. I use some 3/8 inch fuel hose on the end of the oil tip and fill it. Does it just fill to the top? That sounds vaguely familier.

Matt M240Z · 03-17-2006

Just crawled under the car and the only plug that I saw was a hex head bolt on the driver side of the transmission about 3 inches above the oil pan. I assume this is the fill plug? If there is a drain plug, where is it, or do you have to take the oil pan off?

03-04-2006	#1 (permalink)
Bo Mows Bo Know's '69's Join Date: Sep 2005 Location: Olive Branch, MS Posts: 268 Provided Answers: 1	Unanswered: Tranny and rear end oil type? What is the preferred brand and weight of manual 4 speed tranny and rear end oil used in the GT? Just drained both in mine after sitting for 10 years (at least). Bo __________________ Buy it. Build it. Drive it. The rest is easy.

03-04-2006	#2 (permalink)
spdkilz02 1000 Post Club Join Date: Dec 2002 Location: Akron, OH Posts: 1,734	i used regular 80 weight gear oil... __________________ Adam

03-04-2006	#3 (permalink)
asdasc Senior Contributor Join Date: Oct 2005 Location: Mt. Clemens, Michigan Posts: 888	Just out of curiosity, how did you drain the diff? Did you just pull the cover and let it fly? I was looking at mine today and didn't see a drain plug. I must admit, I didn't look REAL hard, but I was thinking about doing what you are. __________________ Steve "ever notice you are never done tinkering with the GT?" Never mind, I am WAAAY beyond tinkering now...[/SIGPIC]

03-04-2006	#4 (permalink)
Bo Mows Bo Know's '69's Join Date: Sep 2005 Location: Olive Branch, MS Posts: 268 Provided Answers: 1	Yep, just dropped the cover and cleaned it out and cleaned the cover and put it back on. I didn't even look for a plug. When the cover came off, it just kinda oozed out. The tranny oil was really new looking. I think the PO did it when he rebuilt the motor. 80 weight in both? Bo __________________ Buy it. Build it. Drive it. The rest is easy.

03-04-2006	#5 (permalink)
spdkilz02 1000 Post Club Join Date: Dec 2002 Location: Akron, OH Posts: 1,734	yeah its just regular gear oil... __________________ Adam

03-04-2006	#6 (permalink)
duaneb Opeler Join Date: Sep 2003 Location: oregon Posts: 97	gear oil FSM for my 73 GT list 80 or 90 wt in both

03-04-2006	#7 (permalink)
Bo Mows Bo Know's '69's Join Date: Sep 2005 Location: Olive Branch, MS Posts: 268 Provided Answers: 1	Lucas Gear Oil? Any comments on Lucas Gear Oil? I really like the Lucas motor oil in my 190,000 + Dodge Ram 318. Never used the gear oil though. Bo __________________ Buy it. Build it. Drive it. The rest is easy.

03-04-2006	#8 (permalink)
hrcollinsjr 2200 Post Club Join Date: Jan 2003 Location: Chapel Hill, TN Posts: 2,263 Real Name: Harold Collins Provided Answers: 14	One of the bottom bolts in the diff. cover will is supposed to drain the gear oil. I put heavy weight gear oil in my tranny years ago. It worked fine until the outside temps started dropping. I got tired of having to force it into gear until it got to a decent operating temperature. Harold

03-04-2006	#9 (permalink)
opelnut10 Living in the past Join Date: Oct 2005 Location: Chesapeake, Virginia Posts: 1,371 Real Name: Lloyd Provided Answers: 2	Gear Lube 80W is fine, I also get a quart of MOROSO high performance lube and put half in the transmission and half in the rear end. It may not help but it don't hurt a thing, it can stand high temps. better than regular gear lube. If you take the top and bottom bolt outta the rear cover after running it up on jack stands it will drain out and not make a big mess. Nothing smells as bad to me as used gear lube and if you get it on you it has to wear off. After you let it drain take the cover off and clean it and fill with lube till you can stick your pinky in the fill hole and bend it at the first joint and touch the lube, just right then. Transmission has a magnet in the bottom of it's pan check it and clean the debre off and fill with the same method as the rear end.

03-04-2006	#10 (permalink)
opelwasp Non Civilian Join Date: Mar 2003 Location: Between Chico and Sac, CA Posts: 1,596 Provided Answers: 1	I always use syntheticgear oil. Royal Purple, Red Line, Castrol Syntec, Mobil, all make synthetics. I run it in my engine after break in, trannys auto and stick, and diffs. __________________ Arguing online is the same as racing in the Special Olympics; no matter who wins, you're both still retarded.

03-04-2006	#11 (permalink)
Bo Mows Bo Know's '69's Join Date: Sep 2005 Location: Olive Branch, MS Posts: 268 Provided Answers: 1	I wondered about using Mobil 1. I have 2 commercial mowers (hense the name Bo Mows) and both use Mobil 1. As gear oil in my 36" walk behind and hydro oil in the 52" Zero turn mower. Will it effect anything if i used it in the tranny and rear without contamination from the previous lube in the GT? Bo __________________ Buy it. Build it. Drive it. The rest is easy.

03-05-2006	#12 (permalink)
layed521 Opeler Join Date: Jan 2006 Location: Las Vegas NV Posts: 62	I have been sold on Lucas gear oils & oil additives. I see & hear the difference everytime I put it in 1 of the vehicles that comes into my shop. I have Lucas 80/90 in my diff & trans. __________________ '71 Datsun 521 '71 Opel GT

03-05-2006	#13 (permalink)
baz opel free after 26 years Join Date: Jun 2002 Location: sunderland england Posts: 4,939 Real Name: barry williams Provided Answers: 4	bo mobil 1 will not be good as it will not work right as a gear oil you need a hypoid gear oil old axles ,old technology ,old type oil fully synthetic oil will kill the seals quick time and put your axle in the junk heep when it brakes down and dont lubricate the gears __________________ Copyright © 2003-2009 barry williams All Rights Reserved save praying to God for sunday today we pray to Nike and run like hell

03-05-2006	#15 (permalink)
2 Fast 4 U Detroit,where my home was Join Date: Oct 2005 Location: Maria - Hoop, The Netherlands Posts: 2,214 Real Name: Erick Provided Answers: 5	To drain the oil of the dif you have to remove the bottom bolt of the cover and leave it open for a while __________________ Opel Ascona; driving one is like living on the edge. Only built from 1970 - 1975 Last edited by 2 Fast 4 U; 03-05-2006 at 01:33 PM.

03-16-2006	#18 (permalink)
Matt M240Z Member Join Date: Nov 2004 Location: SC Posts: 127	How much oil does the 4-speed transmission take on the GT? Also, how do you fill it up? I am changing the transmission fluid for the first time by myself. __________________ "The past is past, the future is now"

03-16-2006	#19 (permalink)
kent Opeler Join Date: Jul 2003 Location: Urbandale Iowa Posts: 196 Provided Answers: 1	what size are the trany pan bolts ? I lost and need all new

03-17-2006	#21 (permalink)
Matt M240Z Member Join Date: Nov 2004 Location: SC Posts: 127	Do you take the oil pan off and fill it up with 2.5 pints and bolt it back on to fill the transmission? I just need to know if that is all that is required before I go to get oil and get the car up in the air. Thanks __________________ "The past is past, the future is now"

03-17-2006	#23 (permalink)
Matt M240Z Member Join Date: Nov 2004 Location: SC Posts: 127	Ok, just got back from Napa with a quart of SAE 75W-90 gear oil. On the back, it says "recommended for all hypoid differentials (conventional and limited slip) and manual transmissions where an API GL-5 or MT-1 fluid is specified". This should work right? And is 2.5 pints really all the transmission needs? Thanks again __________________ "The past is past, the future is now"

03-17-2006	#24 (permalink)
asdasc Senior Contributor Join Date: Oct 2005 Location: Mt. Clemens, Michigan Posts: 888	If I remember right, you refill the trans thru the shift boot. Pull the center console, push the shift boot over to the side, reach your hand in the hole and there is a twist off cover. I use some 3/8 inch fuel hose on the end of the oil tip and fill it. Does it just fill to the top? That sounds vaguely familier. __________________ Steve "ever notice you are never done tinkering with the GT?" Never mind, I am WAAAY beyond tinkering now...[/SIGPIC]

03-17-2006	#25 (permalink)
Matt M240Z Member Join Date: Nov 2004 Location: SC Posts: 127	Just crawled under the car and the only plug that I saw was a hex head bolt on the driver side of the transmission about 3 inches above the oil pan. I assume this is the fill plug? If there is a drain plug, where is it, or do you have to take the oil pan off? __________________ "The past is past, the future is now"

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