10w-40 Oil for 78 GS750?

[Guest]

Howdy,
I apologize if this has already been discussed.
I recently received a '78 GS750. I don't have an owner's manual for it. The bike needs 10w-40 oil, but I'm wondering if I need to buy "motorcycle" oil for it? My neighbor tells me regular 10w-40 is just fine. I'd appreciate any insight any of you might have on this.
Thanks!
Pete

[GSCafe]

I usually have m/c oil on hand but I have done it and would do it if I needed to. My '79 GS550 engine is built like a tank and it will be just fine. It is not like it does anything to push the limits of modern automotive 10w-40. You will have to make your choice about doing it, though.

[bonanzadave]

Welcome to the GSRs !

Any 4 stroke 10w-40 should be fine. Grab a new filter too. If you need more info use the search function with the word Rotella.

Here is your required reading BikeCliff Website

Have Fun - Be Safe

[SlipperyPete]

Thanks for the quick reply, guys! I'll do more research on it. I just got a permit, but haven't ridden yet because I don't have insurance. Hopefully this week. Then I have to practice before heading out on the roads.
Bonanzadave-i'm in Woodbury, MN - where abouts are you?

[bonanzadave]

****Lakeville*****

[Nessism]

I wouldn't use auto oil unless it's your last choice. Diesel oil in 15W-40 is more appropriate since it has more high pressure additives than modern auto oil. Motorcycle oil is fine too but more expensive.

[GSCafe]

I wouldn't use auto oil unless it's your last choice. Diesel oil in 15W-40 is more appropriate since it has more high pressure additives than modern auto oil. Motorcycle oil is fine too but more expensive.

The old GS is a low pressure oil system. Can you elaborate on your diesel 15w-40 recommendation?

[tkent02]

Rotella 15W-40 is used my most everyone on this forum or any other old motorcycle forum. All you need.
If you prefer synthetic oil, Rotella makes that too in a 5W-40. It's all good stuff for the old GS engines.

[tkent02]

The old GS is a low pressure oil system. Can you elaborate on your diesel 15w-40 recommendation?

The high pressure comes in the transmission, which shares common oil with the engine. Very high pressures between the gear teeth as they mesh. It will shred regular automotive oil quickly, but the Rotella withstands it just fine. Also it is OK to use with wet clutches, which in these GSes also uses the same oil as the engine. Rotella is rated JASO MA, which is the Japanese motorcycle industry's seal of approval.

[GSCafe]

The high pressure comes in the transmission, which shares common oil with the engine. Very high pressures between the gear teeth as they mesh. It will shred regular automotive oil quickly, but the Rotella withstands it just fine. Also it is OK to use with wet clutches, which is also in the same oil as the engine. Rotella is rated JASO MA, which is the Japanese motorcycle industry's seal of approval.

Thank you. In my opinion, the difference would contribute to oil longevity. I still think automotive 10w-40 is fine in the older GS engines under a regular oil change schedule. I get that wet clutch plus heat can break down the oil faster than a car would. I will check out the diesel 15w-40.

[SlipperyPete]

Thanks for all the input. It sounds like the Shell Rotella 15w-40 is the stuff to get. Thanks a lot for your help everyone. I'll stay tuned to this forum to see if I can be assistance to anyone as I get more experience.

[John Park]

Thank you. In my opinion, the difference would contribute to oil longevity. I still think automotive 10w-40 is fine in the older GS engines under a regular oil change schedule. I get that wet clutch plus heat can break down the oil faster than a car would. I will check out the diesel 15w-40.

The 'regular oil change schedule' that I found necessary with auto oils was so short that I gave up entirely on them. It isn't just the gears but all the ball and roller bearings that beat the snot out of the 'viscosity index improvers' that make a 10w oil into a 10wXX - for a while, anyway.

Personally, I'd rather just use a high end ester based motorcycle oil in the first place; it's about 10w40 to start [and end] with. But this is a Rotella forum….. and that's all you need.