Manual trans lube - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**70STOVEBOLT** · 11-04-2005, 08:17 AM

What viscosity should I use in my 3-speed Saginaw? Whatever is in it now is
way too thick for cold weather. Would SAE 30 motor oil be ok or does it need to be thicker?
Thanks,
Mark

shelby987 · 11-04-2005, 08:27 AM

I asked the same question a while back, 80w90 was what I was told I needed to look for.....maybe synthetic will help a little more with the cold weather.

shelby987 · 11-04-2005, 08:35 AM

Here is the link to the post I had running a while back, hope it helps!

http://67-72chevytrucks.com/vboard/s...d.php?t=177957

**70STOVEBOLT** · 11-04-2005, 09:54 AM

I think 80/90 is what's in it now, but it is STIFF in the morning. This morning it was 52 degrees and it was kinda stiff. After about 10 miles or so it loosens
up.

**Green Machine** · 11-04-2005, 10:05 AM

I've been using Royal Purple synthetic gear lube in my 3spd, lots thinner when cold, however it has friction modifiers in it for posi rear ends. I think it is a little too slippery for the synchros to work properly, shifting is a little notchy till it warms up. I think Redline makes a manual trans synthetic that has more friction for the synchros to work prperly, I think I will drain my tranny and try that when I have time -my 2 cents. Tranny takes 2 quarts.

soundspecilist · 11-04-2005, 10:21 AM

You are correct. I read someplace recently that the syncro's need a decently thick fluid once the tranny is warm due to the material the syncro's are made of. Apparently in the 70's at some point, the material was changed and early morning shifting became easier. I have an SM465 4-speed with the same problem. Getting it into 2nd is near impossible when it's cold, but when it's hot, I grind the &^%$ out of it going into 3rd. I've heard either a semi-synthetic or just mixing half synth and half reg gear oil should be a good solution. I will be trying this same thing very soon.

shelby987 · 11-04-2005, 10:23 AM

52 degrees is cold

Michigan has been unseasonably warm the last couple of days, I suspect I will find a couple of fluid problems in the next month or so with those zero degree cold starts!
Green, I am going to be switching my fluid this weekend hopefully, I will use the redline and let you know how it works......who sells redline products?

**kwmech** · 11-04-2005, 10:51 AM

Good quality 20/50 cna be used.

**Green Machine** · 11-04-2005, 01:56 PM

Oh, btw, if your 3spd doesn't have a drain, the lowest bolt on the tailshaft can be removed and used as a drain plug, be sure to put some sealer on the theads before putting it back in or you might have a slight drip from there.

TruckinDaddy · 11-04-2005, 02:09 PM

Green Machine, you read my mind. I was searching the site, looking for the location of my 3spd drain plug. Thanks for the info, guys.

11-04-2005, 08:17 AM	#1
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,266	Manual trans lube What viscosity should I use in my 3-speed Saginaw? Whatever is in it now is way too thick for cold weather. Would SAE 30 motor oil be ok or does it need to be thicker? Thanks, Mark

11-04-2005, 08:27 AM	#2
shelby987 Registered User Join Date: Mar 2005 Location: Just outside Durham, NC Posts: 894	Re: Manual trans lube I asked the same question a while back, 80w90 was what I was told I needed to look for.....maybe synthetic will help a little more with the cold weather.

11-04-2005, 08:35 AM	#3
shelby987 Registered User Join Date: Mar 2005 Location: Just outside Durham, NC Posts: 894	Re: Manual trans lube Here is the link to the post I had running a while back, hope it helps! http://67-72chevytrucks.com/vboard/s...d.php?t=177957

11-04-2005, 09:54 AM	#4
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,266	Re: Manual trans lube I think 80/90 is what's in it now, but it is STIFF in the morning. This morning it was 52 degrees and it was kinda stiff. After about 10 miles or so it loosens up.

11-04-2005, 10:05 AM	#5
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Manual trans lube I've been using Royal Purple synthetic gear lube in my 3spd, lots thinner when cold, however it has friction modifiers in it for posi rear ends. I think it is a little too slippery for the synchros to work properly, shifting is a little notchy till it warms up. I think Redline makes a manual trans synthetic that has more friction for the synchros to work prperly, I think I will drain my tranny and try that when I have time -my 2 cents. Tranny takes 2 quarts. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

11-04-2005, 10:21 AM	#6
soundspecilist Registered User Join Date: Nov 2005 Location: Los Angeles, CA Posts: 15	Re: Manual trans lube You are correct. I read someplace recently that the syncro's need a decently thick fluid once the tranny is warm due to the material the syncro's are made of. Apparently in the 70's at some point, the material was changed and early morning shifting became easier. I have an SM465 4-speed with the same problem. Getting it into 2nd is near impossible when it's cold, but when it's hot, I grind the &^%$ out of it going into 3rd. I've heard either a semi-synthetic or just mixing half synth and half reg gear oil should be a good solution. I will be trying this same thing very soon. __________________ '69 GMC C3500 1-Ton, Longhorn, SM465, built 350,

11-04-2005, 10:23 AM	#7
shelby987 Registered User Join Date: Mar 2005 Location: Just outside Durham, NC Posts: 894	Re: Manual trans lube 52 degrees is cold Michigan has been unseasonably warm the last couple of days, I suspect I will find a couple of fluid problems in the next month or so with those zero degree cold starts! Green, I am going to be switching my fluid this weekend hopefully, I will use the redline and let you know how it works......who sells redline products?

11-04-2005, 10:51 AM	#8
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,500	Re: Manual trans lube Good quality 20/50 cna be used.

11-04-2005, 01:56 PM	#9
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Manual trans lube Oh, btw, if your 3spd doesn't have a drain, the lowest bolt on the tailshaft can be removed and used as a drain plug, be sure to put some sealer on the theads before putting it back in or you might have a slight drip from there. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

11-04-2005, 02:09 PM	#10
TruckinDaddy What's that funky smell? Join Date: Mar 2005 Location: Austin, TX Posts: 610	Re: Manual trans lube Green Machine, you read my mind. I was searching the site, looking for the location of my 3spd drain plug. Thanks for the info, guys. __________________ Mike S 68 C10 Long Step (Pretending to be a Long Fleetside) Grandpa's Farm Truck 3 on the tree, 307, No power brakes or steering Factory Options - HD rear spring and Ammeter/Oil Gauges My truck blog My Car Domain page



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