CB750: What motor oil to use?

BArTY

Been Around the Block
Here's a loaded question I'm sure, but I am open to all answers and input.

What motor oil do you CB750 guys run? I've heard everything from partial sythetic to non-synthetic due to wet clutch systems in our engines. I've also read about Shell's Rotella T6 oil as being "the best" oil for our engines. Ton of people rave about it, but its labeled as a full synthetic, though many claim its not truly a synthetic. I'm hesitant to put it in my engine.

What do you guys run, success stories, failures?

Heres a link to the wiki article on Shell Rotella T6 motor oil
http://en.wikipedia.org/wiki/Shell_Rotella_T#Motorcycle_usage
 
Castrol 20/50 MT motorcycle specific oil, no detergents, only about $0.25 more a quart, and the 20/50 being a bit on the heavy side keeps your 30+ year old engine nice and lubed.
 
Remember, Cpt. Square tire is in FL so his opinion is a bit skewed.

;)


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I'll take that as a compliment, yes, down here in FL, 20/50 doesn't affect cold starts since it's 70+ for 11 months. In colder weather, I'd go with 15/40, and keep it in the garage. Oh, and btw, it's not square tires anymore, chicken strips are only about 1" wide now, found a couple of nice curvy roads a few months back.
 
I've used Castrol 10-40 in the passed and had an engine seize up on me. Rebuilt engine needs to be properly cared for from the start so I'm very picky when it comes to what oil I'm using. Heard great things about Rotella and would like to try it but I'm hesitant with it being called a "full synthetic".

P.S. I'm in Southern Cali so 20-50 is probably best for me too. Its friggin HOT!
 
Rotella 'synthetic' also has a 10w/40
I add about 2oz of ZDDP as levels have been dropping for years and have been removed from most automotive oils
'Our' engines were designed when ZDDP levels were around 1800ppm, today, levels are around 1200ppm which is the lower limit.
Just about any diesel oil still has ZDDP in it.
Main reason to remove it is catalytic converters, it 'poisons' them so automakers want it removed.
They have to warranty emissions for up to 5 yrs/100,00 miles 'cat' could be changed at no cost to owner under warranty (could get real expensive, real quick)
I'm running Rotella 5w/40 in all my bikes (with added ZDDP)
 
I have used Castrol 10-40 for over 40 years in all my bikes.
(And I am a Amsoil dealer, and still use Castrol 10-40)
 
Crazypj, do you notice any issues with clutch slippage using Rotella T Triple? I'm doing an oil change this weekend and think I might switch over. Is adding ZDDP necessary or more of a precaution? Should I be adding ZDDP to any oil I use? Thanks guys!
 
I've had some clutch slip on 378 motors, but, I think they would slip even with conventional oil.
I have used Rotella without ZDDP, it may be just an added precaution but my Katana seems to notice the difference
 
I haven't noticed on the 350 (bored out from 325 to 358ish) but I did replace the friction disks and alloys with Barrnett parts.
 
Barnett are pretty 'grabby' and slightly thicker than stock so will have slightly more spring pressure.
I use stock plates and heavy duty springs.
In my experience, ALL 70's Honda clutches slip at high rpm
 
Wolfie said:
I have used Castrol 10-40 for over 40 years in all my bikes.
(And I am a Amsoil dealer, and still use Castrol 10-40)
Non-synthetic? So is that the consensus? 10/40 conventional motor oil is best.
(I take it synthetic causes clutch issues?)
 
and for further reading:
http://classiccars.about.com/od/maintenancetips/a/Zddp-Debunking-The-Urban-Legend-This-Motor-Oil-Additive.htm
 
Rotella. (NOT synthetic) I don't use any sort of additional additives. Viscosity to suit your climate. Take enough engines apart that have familiar oil history and you will be a believer. A couple of years ago I put some in the trans of a two stroke when I didn't have anything else on hand. Made an absolutely noticeable difference for the better! That bike didn't have any trans issues before, or so I thought - super surprised at the improvement. No effect on the clutch detected. Use it universally now.
 
I'm having a few clutch issues and think it might be down to a heavier oil I used (20W 50). I found this Rotella T Triple oil in Canadian Tire -

http://www.canadiantire.ca/en/pdp/rotella-t-15w-40-diesel-motor-oil-946-ml-0287929p.html#srp

- but it's listed as a diesel engine oil. Is that gonna work?
 
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