Full Synthetic or Blend..?

I recently bought a 2003' YZ 450F in pretty good shape and for a really nice price.. The guy I bought it from always ran a synthetic "blend" from when the bike was new..My question is..!! Would it be ok to run full synthetic on this bike..?? I run full synthetic on every piece of machinery that I own (Harley,Cars,Boat, Etc.) but I read somewhere that running full synth on a dirt bike somehow causes clutch slippage or something like that. Is that B.S...?? or a legitimate "fact", please help..!! much appreciated..!!

There is no problem in running full synthetic oils. Synthetics labeled "Energy Conserving II" or API ECII can potentially cause trouble with the clutch, but synthetics made for motorcycles or commercial applications generally don't, and you won't find many ECII oils in the viscosity range you would want to use, anyway. Your main concern is in finding an oil that was blended for use as both an engine and transmission oil, as most engine-only oils can't take being used in a gearbox for more than a couple of hours without loosing their viscosity. More than 60% of premium MC synthetics are blended this way now, but as little as 5 years ago that wasn't true.

Read: Synthetic Oils

what about full synthtic? the guy at my local yamaha store said to use 10-50 full synthetic. the kind he recomennded was for steet bikes i think. He recomennded it over the yamalube oil. he said something about when doing lots of trail riding the yamalube oil foams up.....i just took his word, and bought the full synthetic oil......also i have a buddy that uses diesel oil in his KTM. he said it works better and you can get a gallon of it for ten bucks....any word on either of these two opinions???

I knownquite a.few.people that use rotella

I knownquite a.few.people that use rotella

Stay away from Rotella.

I know rotella now caries a JASO MA certification but it is intended to be used in a diesel engine that gets it oil changed every 200-400 hours.

Because Rotella is used in this type of environment, it is loaded with detergants, dispersants, pH stabilizers, and othe additives that have no use in a dirt bike engine, however some marketing genius at Shell cought wind of people using Rotella in their motorcycles and managed to get it certified.

These additives displace the base lubricating oil and offer no improvement in lubricating quality. Additionally, these additives do not hold up well in the transmission and deteriorate rapidly into chemical 'debris' that furthur degrades the performance of the oil.

As far as syntehtics go, thanks to Mobil losing a dispute to Castrol about the rights to use the term 'synthetic' on an oil label, there is a lot of confusion.

There are five catagoies of lubricating oil; Group I, II, III, IV, V. Before the Mobil dispute only Group IV and Group V lubricating oils were considered true 'synthetics'. Group IV a.k.a. PAO (polyalphaolefin) and Group V. Group V oils are non-PAO synthetics; ester, diester, polyester, alkylated hydrocarbon, etc.

Group I, II, III were all classified as mineral or petroleum based oils until the early 2000's

Thanks to slick marketing by Castrol when they introduced their Syntec brand of oil (a Group III oil, not synthetic), oils marketed in the United states that are made from Group III base stocks can now be labeled as 'Synthetic' oil.

True Group IV and Group V based lubrication oils are superior in every way to other oils but it's not an easy task to figure out who sells them. Maxima, Spectro, and a few others do sell a 100% ester synthetic oil. 100%ester synthetic oils usually cost in the $12-$18 per quart range.

IMHO, synthetic blends are a waste of money and oils marketed as such usually aren't blended with a Group IV or Group V synthetic. They just use a hydrocracked Group III oil and bend the rules to label them 'Synthetic'.

Edited by 2grimjim

You are correct about Group III oils. Casrol's argument was that their oil was so thoroughly refined that the process amounted to synthesis, and a court bought it. Not all full synthetics have bought into that cynicism, however,

This I know for a fact: Mobil 1 Racing 4T and V-Twin oils and Amsoil MCF and MCV "Synthetic Motorcycle Oil" use pure polyalphaolefin base stocks, and contain additives that allow the oil to retain viscosity for much longer than not made for the purpose. The top of the Maxima line uses Group V ester base stocks, and some of the lower level full synthetic Maxima stuff is a blend of ester and PAO. These oils are also blended with transmission grade additives. In spite of the fact that the lower level Maxima Synthetic/Petro blends and oils like Golden Spectro 4 are not full synthetics, they still do have the ability to hold their own in a transmission.

If you think that your Rotella will stay together in your YZF gearbox over time, all you have to do to prove it to yourself is to run the stuff to your usual oil change interval and send off a used sample to a lab like Blackstone. When you get the results back, look at the measured viscosity at 200 ℉. Last one of these I saw for Rotella a couple of years ago showed an oil sample with 3 hours on it measured as a 5w-25, not the 5w-40 it started out.

Well I give my .02cents, I run the synblend maxima in my toys.

I have a dragged out yfz with a lockout clutch and when I went to maximas full synthetic oil it started slipping instantly!

So I went back to the blend as they call it and have no issues.

I have a dragged out yfz

Nothing more need be said.

I just bought some Silkolene 10W-50 Pro Plus 4T Fully Synthetic.

Waiting for it to arrive from TT then, will throw it in the YZ.

At the moment it has Motul 10W-50 non-synthetic.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now