Oil questions?

I just bought a used 98 WR400 with no owner's manuel. I ordered a shop manuel but I would like to change my oil before I ride this weekend. Can anyone tell me how much oil is required and what weight oil to use. Also any recomendations on oil brands and how often to change the oil.



98 WR400F

To drain the oil it helps to warm the bike up but this isn’t necessary. Drain from the frame reservoir first, there is a 12 mm hex-head bolt just above the skid plate in front of the bike just behind the front fender. Hold a suitable container up to the drain area or the oil will spill.

Then drain the cases, another 12 mm hex-head.

Then inspect & clean/replace the filter, if your bike has the stock headpipe you will need to remove it by loosening the tailpipe connection and removing the allen-head bolt and 12 mm hex nut at the cylinder.

To get the filter out remove the two 8 mm hex head and one (5 mm??) allen head bolt from the round filter cover just to the rear of the water pump on the right side. I like to lean the bike over on me a bit and have a container ready so that oil from the filter housing it doesn’t get all over my motor and the floor (but drains directly into the container instead).

Sometimes the rubber gaskets on the filter will stick to the cover or the inside of the housing. Make sure you retrieve both gaskets (and reattach to the filter if you plan on reusing it) before putting another filter in. The filter will only go in one way.

The filters are made of a metal screen, not paper, so you can clean and reuse it as long as it isn’t torn and the rubber gaskets are in good shape. The oil flows from the outside in, so clean it by backflushing it from inside out.

Oil capacity is 1.7 liters (like 1.8 quarts or so). If you don’t inspect/drain the filter housing it will take a bit less but I don’t see the point in changing the oil if you don’t inspect the filter and get all the old oil out.

The manual recommends Yamalube 4R but I forget what weight (20w-50 maybe?). I quit using that stuff, IMO it is overpriced, and I use Mobil 1 automotive 15w-50 instead. Other weights have additives that MAY be bad for your clutch (said additives noted by Energy Conserving or “EC” label/designation).

Mobil 1 also makes a motorcycle specific synthetic, I saw some at Auto Zone the other day but I just buy the car oil and save a few bucks.

I change my oil every three to six hours (basically every weekend that I ride it or every race).


Thanks for the detailed instructions.



98 WR400F

The most recommended weight is 10/30W..

DO NOT USE a friction modified formula oil. That means ALL car oils that ive seen (not sure about the 15W/50 Mobil 1, and honestly its more than likely got Friction modifiers., but as mentioned, mobil 1 makes an oil stictly for motorcycles).

Its slippery characteristics cause the clutch to slip. 20/50 can be used but it robs too much Hp. No more than 10/40 or if you like to run in 100 plus heat all day long.

And the detailed info is spot on. Even My 01 Wr426 uses the same method of oil changing.


[This message has been edited by Jemtec (edited 04-07-2001).]

[This message has been edited by Jemtec (edited 04-07-2001).]

10w/30 is too light unless you ride only in temps less than 60. I use 10w/40 at 60 and below and 20w/50 above. In that weight castrol gtx is not energy conserving. My oil is changed after every ride, $1.08 a qt. keep it clean. mike

From my years selling autoparts and Oil, 20/50 and 10/40 Engine oils dont have the agressive Cleaning action that 10/30 does. Unless you are running an Airhammer, The liquid cooling lowers the wear on the oil by leaps and bounds. Oil is not like the old days when "thicker" is always better. It does provide more protection from high tempratures and extreme pressure, but thats mostly in racing Car and Truck engines that are ran all out for great periods of track time, or Severe Work loads that generate tons of heat.

These days, Bikes work hard..but cool well. So, Its really just alot of extra fluidic friction to run heavy weight oils. I honestly would stay away from 20/50. :)

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