The 10W-40 that the dealer recommends is to thin and my dealer told me NOT to use synthetic because it causes the clutch to slip. I've read that a lot of people in here use Mobile 1 15w-50. Have you had any slippage problems? Any info would be appreciated.

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I've been using Mobil 1 15w50 in all our quads (trx90, 250x, 400ex, Recon) since '95 and I've never had ANY problems.

 

I ALWAYS use Mobil 1 full synthetic 15w50 oil in my 300ex which has the same type of clutch as your 400ex and i never have any clutch slippage.
Personally i think its all bull because the dealerships want you to buy their "special" atv oil.
Dont fall for it. A ton of other people in this message board use mobil 1 synthetic oil in their quads without any trouble at all, and so do I.
Mike

 

is it better to run synthetic or regular oil. cause i need to change the oil in my 250X, and i wanted to go to a heavier weight than 10w40, cause it just doesn't hold up here in ohio during the summer. what do you guys recommend?

 

I run the GN4 10-40 oil in my 400. I was told the same thing, syn. oil in quad=clutch slipage. of course he couldn't answer when I asked why then does Honda market a synthetic racing oil. DUH! I am thinking of switching to Maxima semi-syn. 10-40 for my next change. Just because I swear by Maxima 2-stroke oils.(My old Blaster and my many previous dirt bikes).
Why is everyone using car oil in their quads? It's not designed to be run in a wet clutch set-up. If you haven't had slipping yet your very lucky. It can seriously shorten the life of a clutch.

Just stick with motorcycle oil. Whether it's syn. or regular it's your choice.

 

400exrydr, do the head pipes stick out a lot further than stock on your DMC? What about a heatshield, does it come with one? I ask because I've heard of people burning their riding pants because the head pipes stick out to much. I really don't want to buy a $100 pair of pants everytime I ride.

Thanks for the help.

 

After reading an excellent review of motor oil performance, I run nothing but 10W-30 oil in all of my engines. According to the article, multi-viscosity oils are made from a base-weight oil (10W for example) and non-lubricating additives which thicken as the oil heats up. Naturally then, oils which carry a wider range of viscosity performance must include a higher percentage of the non-lubricating additive per unit volume. This translates into less lubricating oil in the oil pan to create the protective barrier between rotational surfaces.

It does seem to make sense when you think about it.

I should also add that a problem with a sticking valve in my wife's van went away soon after I switched from using 10W-40 to a 10W-30 weight oil.

As for synthetic oil, I prefer to call it "idiot oil" since it helps those who seldom change their oil. It will retain exceptional lubricating performance much longer than a conventional oil. For this reason it is often found in commercial applications. It is a matter of opinion as to whether it's ability to outperform conventional oil under normal (recommended oil changes) conditions justifies the additional expense.

 

Hey me400ex
I can't say about 400ex's because i own a 300ex but i can say that my supertrapps pipe does stick out further than the stock pipe did. It doesnt stick out so far to be really annoying but it can get hot when you put your leg close to the side of the quad while leaning into a turn.
Mike

 

Here's what I've learned:
1. 10W30-10W40 is good ALL-AROUND oil from freezing to 80 degrees F
2. 15W50-20W50 is good for 40 degree and much higher temps, and may be the better choice for racing or hard riding in summer months.
3. *Fully* synthetic oil CAN cause some slippage in the clutch.
4. Regular oil changes, based on riding conditions and frequency, no matter what kind you use, is the best thing for a car, ATV or any kind of combustion engine. However, synthetic-blend oils will last longer.

I was going to start using only Mobil-1 (as I do for my car), but, after reading 2 or 3 mag articles about 100% synthetic oils being VERY GOOD for internal engine parts, but causing slippage in clutches, I am going to stick with Synthetic/Petroleum blend 4-Stroke oils.

Interesting tidbit: Honda's new CR450F has SEPARATE oil sources for the engine and for the clutch. Why? They want the slipperiest stuff
available for the engine (100% synthetic), but they need something less slippery for the clutch....that speaks volumes to me.

So I now use only Synthetic/Petroleum BLEND:
10W40 fall/winter/spring
20W50 in the summer

Again, my .02

 

As for synthetic oil, I prefer to call it "idiot oil" since it helps those who seldom change their oil

I like to call conventional oil "idiot oil" since people still running it in their air-cooled or heavily abused ATV engines must obviously think extended oil change interval is the only value of synthetic oil...

Do some real research & get back with us...