What's the best oil to use in 'ol 426

Does anyone have a recommendation on oil? I have used Belray Exp, but wonder if something better exists.

I just replaced the piston and cylinder. The cylinder was dimensionally correct except for grooves on the top and bottom from the rings, probably caused when the piston changed directions. The bike was smoking excessively at start up and compression was fading. BUT NOW IT RUNS LIKE A CHAMP.

I would like to know some opinions on the best oil to prevent wear and not jag up the clutch.

I use Amsoil synthetic in all my motors (cars, truck, lawnmower, etc). They have 4 stroke ATV, 2 stroke, etc, etc. Their wear tests beat everything else. Lots of racing teams use it. I've never had a problem with any of my engines. You need to break in the engine with regular oil though. The friction is low so running it on breakin won't allow seating as easily. Lots of dealers around or you can order direct from their website (pay the $20 for a year and you get mondo discounts). It's a bit pricey but with the cars, you can go up to about 30,000 mile drain interval. My first bike with Amsoil was my '84 XR250 and it still rocked when I sold it earlier this year. They've been around since the 70's.

I used to use Amsoil 2cycle in my RM. I liked it. Didn't know that they made motor oil. I will look into it. THanks.

alot of people use mobiel 1 15W 50 tri synthetic. That is what i use.


Yep, Amsoil makes all kinds of stuff now. Had a dual filtration system (bypass remote filtration) for a while for one of my cars. I almost became a dealer until I found I could get the same pricing for $20 a year as dealers get.

Mobil just release a true synthetic call MX4T in a 10W-40 that was specifically designed for motorcycles. The only place I could find that was carrying it local was Autozone. I know of a couple of people that are running it now, so no reports on the wear yet.


I am thoroughly confused here. My manual states that a 10w-30 should be used in the colder months <40 degrees and a 20w-40 should be used in the warmer months >40 degrees. There are two suggestions to use different grades. I'm much more apt to be ultra-religious about oil changes if I can use soething that's not $12 a change (Yamalube). What else can be used in the hot months?

I hate to admit it but the local honda dealer sells thier 4 stroke oil to me ( or anyone else for that matter )

for about a dollar less then the Yam dealer sells yamalube for, also I have used valvoline semi sinthetic motor oil

(10-40) with good results . I change my oil every 300 miles and filter every other oil change.

I also swear by Amsoil's synthetic "motorcycle specific" oil, without the friction modifiers found in automobile oils which could jag up your clutch. For break in, use non synthetic (like Yam's 20W40) for first couple hours of break in, and again for a couple hundred miles...Amsoil's 10W40 is good for a wide temperature range. I use their 0W40 in our cold spring and fall; Its viscosity is actually as high as the 10W40 in warm temps. Unless you're racing in some hot desert, thicker oil would only slow you down...

I always was told NEVER to put a synthetic oil in a engine with a wet clutch. Maybe I am taking it too far..

Isn't the synthetic oil too "slippery" for wet clutch applications?

Also how does the synthetic oils affect clutch materials?

Since you guys are changing your oils as much as you do Why bother with the extra expense?? The oils today, even the cheap stuff is top notch.

I am curious about the synthectic. Let me know.

Synthetic oils sometimes have "moly" additives and thats what you want to stay away from. :)

From my understanding, stay away from synthetics for the first 500-1000 miles. It will not allow the enging to correctly break in. Eric Gore told me this after seing my 426 cylinder. Motorcycle desingned synthetics are fine after that. They will not harm the clutch. How many motorcycles have a dry clutch? I run Maxima's non-synthetic. I will switch to sythetic sometime after 500. Klotz synthetic 20-50 or 10-40 work awesome. The Bellray Thumper oil is a blend and may be promising. I think the blends have a better cushining effect. Yahmaha 4R is a blend. This is just my take listening to the pro. Hope it helps. ---Mike

Thanks for the feedback.

I change my oil every 2-3 rides. Synthetic is pretty expensive for oil. Is it worth the money??

I have been using semi-snythetic oil in my Yam. My local autozone just started carying Valione motrcycle specific oil. I don't think it is synthtic at all. So should I buy semi-synthetic for $2.39 or MX specifc non-syn for $2.99 :D:):D

i run the belray exs oil it fully synthentic and i have had no problems with the clutch slipping. I run the 10w-50 all year round and it works perfect although a little tough to start in -20c.

The guys in the car forums I participate in have beaten this issue to death. Most synthetics are not what you think they are, yes they still are dino based oil. You should run oil design for motorcycles. The most important reason being the zinc content in car oils is far reduced due to cars having catalitic converters, zinc helps control wear on things like the cam.


Like Tony426, I too use Honda oils :). I've used GN4 10w40 in all my four stroke bikes.

I think you can't go wrong with Motorcycle specific oils provided they meet all the requirements set out in the WR owners manual. The key is to keep the engine free of contaminants by changing your oil and filter frequently. An oil/filter change only takes five minutes. I keep a spare metal oil filter handy for quick changes, clean the old one out with contact cleaner and reuse @ the next oil change.

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