Gear oil in a SM465? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

eric67m · 11-09-2008, 11:02 PM

I just put in a new (to me) 4 spd / np205 into my 67 K10. When I was refilling the cases I used the remainder of a 80-90W GL-5. The other new bottle that I had around was 90W GL-1 mineral gear oil. I used it only in the transmission. I have not driven it yet but am wondering if it will do any dammage or if I can drive it as is?

Old Yeller 1970 · 11-10-2008, 12:58 AM

I don't know much about 90W mineral oil except that it was used a lot in tractor hydraulics from 50 years ago and Fiat transmissions. Since SM-465's and np205's are nearly indestructible and you have a mix of proper 80-90W and 90W mineral I'm going to guess you'll be all right.

eric67m · 11-10-2008, 01:33 AM

Transfer case is 100% 80-90W

Transmission is 95 ? % mineral gear oil. Still not fully filled. Started to rain and pumping gear oil sucks.

I just know it would be cheaper to throw out this gear oil and go with what I know is proper than screw up my transmission.

Old Yeller 1970 · 11-10-2008, 01:43 AM

Quote:

Originally Posted by eric67m

I just know it would be cheaper to throw out this gear oil and go with what I know is proper than screw up my transmission.

If nothing else, you'll sleep better at night too.

**'68OrangeSunshine** · 11-10-2008, 08:36 AM

I use 90 wt GL-5 in both my SM465 and posi rear end. I bought a 5 gallon can of it.
The rear end needs the GL-5 to lubricate the clutch plates in the positraction. The manual tranny only needs to be cushioned by the heavier viscosity of a 90 wt. I think your 465 is fine with he mixed oils.

eric67m · 11-10-2008, 09:04 PM

I just drained out the mineral stuff and then I put 1 gallon into the transmission and it is still not full. Seemed like I only used about 1/2 gallon in the transfer case. According to the manual (probably for the sm420?/timken) they take a total of 11.25 pints which equals 1.406 gallons. I guess I will go buy another gallon tomorrow.

Old Yeller 1970 · 11-10-2008, 09:37 PM

While you're at it, here's a little tip to keep your input and output shaft seals from leaking. Add a few ounces of DOT 3 brake fluid. Over time seals in any transmission get old, hard and start to leak. The stuff in break fluid makes the rubber soft again where it will keep a tight seal. I've used it to stop the front main seal of my '94 Burb auto tranny from leaking. Ditto that in the power steering pump on an old '86 GMC beater. And likewise in my SM 465 in Old Yeller.

11-09-2008, 11:02 PM	#1
eric67m Registered User Join Date: Apr 2005 Location: Monroe, WA Posts: 298	Gear oil in a SM465? I just put in a new (to me) 4 spd / np205 into my 67 K10. When I was refilling the cases I used the remainder of a 80-90W GL-5. The other new bottle that I had around was 90W GL-1 mineral gear oil. I used it only in the transmission. I have not driven it yet but am wondering if it will do any dammage or if I can drive it as is? __________________ 67 K10, lwb, fleetside, 327, 4spd, 205, cab and 3/4 frame swap, 14 bolt, big window, and a "rustoleum roll job"

11-10-2008, 12:58 AM	#2
Old Yeller 1970 DON'T TREAD ON ME Join Date: May 2005 Location: Crosby County, TX Posts: 989	Re: Gear oil in a SM465? I don't know much about 90W mineral oil except that it was used a lot in tractor hydraulics from 50 years ago and Fiat transmissions. Since SM-465's and np205's are nearly indestructible and you have a mix of proper 80-90W and 90W mineral I'm going to guess you'll be all right. __________________ Old Yeller

11-10-2008, 01:33 AM	#3
eric67m Registered User Join Date: Apr 2005 Location: Monroe, WA Posts: 298	Re: Gear oil in a SM465? Transfer case is 100% 80-90W Transmission is 95 ? % mineral gear oil. Still not fully filled. Started to rain and pumping gear oil sucks. I just know it would be cheaper to throw out this gear oil and go with what I know is proper than screw up my transmission. __________________ 67 K10, lwb, fleetside, 327, 4spd, 205, cab and 3/4 frame swap, 14 bolt, big window, and a "rustoleum roll job"

11-10-2008, 08:36 AM	#5
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,517	Re: Gear oil in a SM465? I use 90 wt GL-5 in both my SM465 and posi rear end. I bought a 5 gallon can of it. The rear end needs the GL-5 to lubricate the clutch plates in the positraction. The manual tranny only needs to be cushioned by the heavier viscosity of a 90 wt. I think your 465 is fine with he mixed oils. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

11-10-2008, 09:04 PM	#6
eric67m Registered User Join Date: Apr 2005 Location: Monroe, WA Posts: 298	Re: Gear oil in a SM465? I just drained out the mineral stuff and then I put 1 gallon into the transmission and it is still not full. Seemed like I only used about 1/2 gallon in the transfer case. According to the manual (probably for the sm420?/timken) they take a total of 11.25 pints which equals 1.406 gallons. I guess I will go buy another gallon tomorrow. __________________ 67 K10, lwb, fleetside, 327, 4spd, 205, cab and 3/4 frame swap, 14 bolt, big window, and a "rustoleum roll job"

11-10-2008, 09:37 PM	#7
Old Yeller 1970 DON'T TREAD ON ME Join Date: May 2005 Location: Crosby County, TX Posts: 989	Re: Gear oil in a SM465? While you're at it, here's a little tip to keep your input and output shaft seals from leaking. Add a few ounces of DOT 3 brake fluid. Over time seals in any transmission get old, hard and start to leak. The stuff in break fluid makes the rubber soft again where it will keep a tight seal. I've used it to stop the front main seal of my '94 Burb auto tranny from leaking. Ditto that in the power steering pump on an old '86 GMC beater. And likewise in my SM 465 in Old Yeller. __________________ Old Yeller Last edited by Old Yeller 1970; 11-10-2008 at 09:38 PM.



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