Which lube works best with a SM465?

[DerekTheGreat]

I'm currently running what the owner's manual suggested, gear lube of mumble-mumble viscosity. But, the thing shifts like a turd. I was wondering if people have used the special lube required for NV4500's in an SM for improved shift quality. What about ATF? Heard one guy used motor oil but that didn't work out well for him haha. What have you used with your POS SM465 before you threw a grenade at it?

 

[someotherguy]

The special (and expensive; $20ish/quart) fluid for the NV4500 is specified because of the carbon fiber-impregnated synchros that those transmissions use. It's not going to do anything for your SM465, so don't waste the money.

SM465 is a heavy duty transmission. It's never gonna shift like a sports car. Run the specified lube and live with it, IMO, or swap it for something else. (By the way even an NV4500 shifts like a "truck" transmission, though it is somewhat better behaved than earlier stuff.)

Richard

 

[DerekTheGreat]

Ah. Thanks for the technical info, it's nice to know why something is specified over something else.

I know about the trans and it's purpose. Off road people seem to like them a lot and I appreciate how stout it is but it shifts like crap. I've test driven two different trucks with NV4500's and they all shift smooth compared to my SM. Trying to find a parts truck to make swap happen but who knew a gas C2500/3500 long box regular cab would be hard to find?

 

[Biggershaft96]

When i had mine i used penzoil syncromesh. It quieted it down a bit but i dont think you can get them to not shift like a turd. These things are amazing off road and are deisgned to be behind big blocks and pull stuff. They are super strong but there is nothing you can really do to make them shift better. A second or two delay between shifts is normal.

Edit: Sorry those last 2 posts wernt there when i loaded the page

 

[DerekTheGreat]

Can't wait to throw it in the garbage. Around me, people can't give them away. Guess it's in good shape though, it has a delay like you mentioned.

 

[someotherguy]

Don't be so quick to shitcan that SM465. If you can stand to have it sit around a while, you can sell it for a few bucks. Also remember yours is most likely a fairly uncommon variant of it; should have an aluminum top cover and an extra switch - that switch was for the TBI trucks that signalled the ECM to go into a lean mode for fuel economy when you're in 4th gear (man I hope I'm remembering all that correctly.)

If you're hunting an NV4500 for a swap just be careful what you buy. If you can't test it, assume it needs a rebuild. There are a couple known weak links in them...and one of them are owners that will do anything to not spend $100+ on the correct fluid for it. If you can test it, watch for ANY grinding between gears. It won't be as simple as just replacing some synchros. You'll probably be into it for a full rebuild as the chunks will have torn up the bearings and such...expect to spend up to a grand making it right. AND...since New Venture has been out of business for a while, those fancy carbon fiber synchros are no longer available, so you go with aftermarket bronze/brass/whatever, so you lose some of that magical shift feel. Which I guess also means you'd no longer need the expensive fluid and could run anybody's synthetic lube as long as it matched the viscosity and other additive requirements (I'll assume GL4 so it doesn't attack the yellow metals.)

Richard

 

[DerekTheGreat]

Ok, I'll try to hold onto it. The ones I've seen for sale are typically 4x4 ones or all iron. It does have that extra switch but theres nothing in my GM service manual about it and I'm not sure how to check to see if it's working with my scanner, an MT2500. Truck just goes from lean to rich back and forth when I'm looking at it while cruising.

Ah, well that sucks to know about the syncros. This is exactly why I want a running parts truck. I don't trust anybody's word on craigslist about how great something is without being able to verify that myself. The two trucks I did test drive both seemed to have transmission related issues, couldn't tell for sure, like worn input shaft bearings. They both shifted easily though. Almost as smooth as the M50DR1's I'm used to.

 

[JDHammond]

http://numberoneoil.myamsoil.com/

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Very good product. If anything would help it would be this! Let me know if you have any questions.

Thanks,

Joe

http://numberoneoil.myamsoil.com/

 

[DerekTheGreat]

I don't know what it is, but I can't get behind Amsoil. No personal experience with their products but a few years ago when I switched from Castrol to Valvoline it was after looking at the results of SAE testing. In test was Amsoil, Royal Purple, Castrol, Valvoline and a few others, synthetics. RP was pretty bad compared to the others. Valvoline wasn't the best but was damn good in tests I thought were significant, even edging out Mobile One.

 

[someotherguy]

Amsoil is the #1 rated oil among people that sell Amsoil.

Richard