Just topped up my oil, used a litre on the last trip, but it is due for an oil change. Have been using Yamaha JASO MA 15W50. Weather here is always warm, last trip was 37degC during the 5 hr rides. Royal Purple is available here in Australia, is it better than the Yamaha stuff and should i change grades?

YAMAHA is not in the Oil Business.
Yamaha is in the Plastic Bottle Business.
You are spending extra money for the Plastic Bottle you discard.

Use 20W40 if you can find it.***
Yamaha recommends this viscosity.
It comes in Bottles Yamaha buys by Truck-loads.

For MAXIMUM Protection and to reduce the amount of Oil you are "Using", ...
Try using a 20W~50 and see how well the Bike runs.

Considering i'm paying $45.00 AUD for a 4ltr Yamaha plastic bottle, i might try Castrol at half the price! Thanks for the comments.

Don't feel so bad, ...
There are people paying $7.99US @ Quart who think Harley~Davidson is in the Oil Business.

Harley pretends to be in the Oil Business when you bring a Bike in for Service.
Look at the Work Order from some Harley worshiper who just had a 5,000 Mile tune-up.
Gen-you-whine Har-lee Davidson Oil.
$8.79 a Quart
The technician fills a Oiler from a Drum of Oil that says Amalie Oil

hi ive got all my casings off for polishing after PO sprayed with aluminium paint..... everywhere ugh!!,anyhow i found oil emulsion in clutch and gears covers, i know there is the breather to the airbox,but inside the gear casing there is some kind of baffle, has anybody serviced this?.Ive got heavy duty clear laquer for protection of my now mirror finish covers (especially clutch cover centre HeHe) will this protect my pristine covers from the dreaded oxidation? also are the cranckcases silver/grey or aluminium? im a printer colour is my business, but i cant make my mind up on that one.
1993 XJ900F

Have no fear removing that Baffle.
Has to be done to "Make-yer-own-gasket"

I've had it off my 83 900 RK several times.
I remove the Baffle.
Apply a thick coat of some birds lipstick, and place the Cover down on some Gasket Paper and the Lipstick leaves a perfect impression for where to cut.

Lipstick! What a cool idea. Why didn't I think of that?

Thanks for the tip, Rick, I'll use it for sure.

i would like to add a ???? MY 82 550 is finaly done it starts and idles awsome lpus is really strong on the road however is trowing oil all over trough crankcase breather could that simply be to much oil or could it be something else..
??????

AHA! Just the thread I need!
I recently acquired a 1982 XJ650 and am loving it (my first bike ) and am not sure what oil to put into it. The guy I bought it from only had the bike a few months (lost his job) and said he changed the oil once and used synthetic instead of regular oil that had always been used in it before. I've read that in old bikes it's best to use mineral oil? Should I continue using synthetic or switch to regular oil?
Thanks!

Mosee.biker:

If you want to make sure your using the right Oil to protect the Bike 100% ... whether all you do is Putt-putt around town, ... or wish you had a switch to throw to add Afterburner's to Wide Open Throttles while you are in the Full giddy-yap Mode trying to catch-up with some guys a quarter mile up-ahead you on the wide-open road ...

Castrol
GTX- 20W-50
Racing Oil

Is
Castrol
GTX- 20W-50
Racing Oil
Great for an 82 XJ750 Maxim also? Suggestions for local stores that might carry it?

This close enough?
GTX oil at Autozone

I'd use it without difficulty. Great stuff and I use it myself.

Good I like buying the basic stuff locally

I recently spoke to a Castrol Representative after a Member complained about Castrol GTX 20W/50 making his Clutch Slip.

The Castrol Rep. said that back in 1996 the formulation was changed slightly and GTX 20/50 now carries an API "SJ" rating.
The formulation was changed to add an ingredient to make the 20W/50 Oil safe for Cars and Light Trucks with Catalytic Converters.

The Company said that they got a few complaints about Motorcycle Clutches slipping, on GTX, but not enough to place the blame exclusively on their product.

Consequently, to cater to the Motorcycle community which want the protection of 20W/50 Motor Oil formulated specifically for use in Bikes with Wet Clutches, ... Castrol recommends using their 20W/50 4-T Brand.

Castrol 4T Motorcycle Oil — Outstanding Protection for 4–stroke Engines

* Provides maximum protection against viscosity and thermal breakdown
* Provides superior engine wear protection, high–film strength and oil oxidation protection for high revving motorcycle engines
* Specialized additive package contains anti–oxidants, detergents, dispersants, and varnish inhibitors that help prevent ring–sticking and build up of harmful engine deposits
* Exceeds the performance requirement of North American and foreign motorcycle manufacturers calling for API SG or JASO MA

* Available in SAE 10W–40 for most motorcycles and also SAE 20W–50 for larger displacement engines, including V–Twins
* Meets API SG and JASO MA2

They also make a Synthetic for those who think Synth is better than Dino.

Enough Synth to do an Oil Change is almost $35.00