Semi synthetic oil vs. regular

Tom Ludolff · Oct 21, 2002

If I change my oil every 100 miles, will I get more life out of my tranny using semi synthetic oil rather than regular motorcycle oil, or is the semi synthetic a waste of money??

Tom L.

kevinkdx · Oct 22, 2002

I use a fully sythetic oil From KLOTZ and when I had the cases split, the gears and the clutch all looked like brand new practically and I run that in my KDX 250 1993 which is far from brand new but I ride it almost every day.

tigerowner · Oct 22, 2002

The biggest advantage of synthetics are their ability to absorb acids created through combustion (that do get in to tranny oil) and their greater sheer strength (oil stays between the parts under greater pressure). Now you do not need to spend a fortune on oil to get protection. Mobil 1 15w-50 is still safe to use dispite the misinformation running through the forums. Synthetic diesel oils such as Shell Rotella-T 5w-40 and Mobil Delvac 1 are also clutch safe (along with the dino versions). Rotella-T synthetic can be found at Walmart for $13 a gallon.

Rich Rohrich · Oct 22, 2002

Originally posted by tigerowner
The biggest advantage of synthetics are their ability to absorb acids created through combustion (that do get in to tranny oil)

How exactly do "acids created through combustion" happen to find their way into the gearbox on a two-stroke?

Dazza · Oct 22, 2002

I think the "acids" corrode a hole in the cases.

tigerowner · Oct 22, 2002

exhaust blow by, unburned fuel and 2-stroke oil draining past the piston. Ever heard of a flooded engine, the gas doesn't magically dissapear. It can run down the cylnder past the piston. Contamination is not as severe as in a four stroke but it can happen.

Dazza · Oct 22, 2002

unburned fuel and 2-stroke oil draining past the piston

Ever heard of how a 2 stroke works?
There is always un burnt fuel under the piston.This is how a 2 stroke works.
The gearbox is totally sealed from the crankcase.
Fuel can not get to the gearbox oil unless the crank seals are shot.
I am asumming you ride a 4 stroke

Tom Ludolff · Oct 22, 2002

Tigerowner,
So you're saying it is not necessary to use synthetic oils specifically designed for motorcycle wet clutches?

Jim Crenca · Oct 22, 2002

There might be a sniper on the loose here in Silver Spring, MD, but it is always comforting to know that Rich is protecting DRN from ignorance ;)

Use synthetic oil because it is better and change it often. Many KDX riders use Mobil 1 15W50 and change it every 100 to 200 miles. Goods threads on this topic here and in Advanced Tech; use the search function.

tigerowner · Oct 23, 2002

Look if there is no possible way for gas to make it to the tranny oil that is great and I appologise for any ignorance. I am not a mechanic and stop at top end rebuilds. I did however metion the two advantages of the oil. I suppose that 2-stroke riders gain most from the sheer strength if this is the case. THe fact that the oil stays between the metal is good enough for me to use it.

As far as motorcycle oils vs. the rest most auto oilsnow have friction modifiers that will cause clutch slippage. If an oil has an Energy Conserving label do not use it. According to several petrolium engineers on the web and personal emails from oil companies themselves the heavy duty diesel oils are similar in composition to motorcycle specific oil and do not contain friction modifiers. They also are formulated to be used under extream loads of large Diesel equipment. These loads are much greater than the loads in a motorcycle transmission. Ask the oil manufacturers yourself as I have and save some money.

BadgerMan · Oct 23, 2002

Based on my limited experience and research, synthetics tend to retain their viscosity better than dino oils. The best evidence I have seen is when using Mobil 1 synthetic ATF in shocks. It looks and feels as good as new every time I change it out.

I use synthetics for everything anymore and in most cases it’s Mobil 1. Red cap 15w-50 in my YZF, MX2T at 40:1 for the kid’s KDX, ATF in shocks and forks.

BTW, changing the tranny fluid in a 2-st every 100 miles seems a bit extreme, IMO.

Jim Crenca · Oct 23, 2002

The 15W50 weight of Mobil 1 does not have the EC label or friction modifiers and does not seem to cause clutch slippage.
I have noticed that shifting isn't quite as good after about 200 hard miles regardless of oil brand or type. That works out to about $1 per ride for me; aprice I'm willing to pay.
You could probably run Pep Boys oil & never change it in a stock KDX, but if you modify the bike & run it hard, I think that changing good oil often is a cost savings in the long run.

BadgerMan · Oct 23, 2002

I drain the Mobil 1 15w-50 out of my YZ250F after every other ride and dump it into my lawn mower! LOL! However, it is not subjected to near as much heat in a KDX tranny so I would think you could get twice the life out of it, or more.

BRush · Oct 23, 2002

At the risk of going against the grain, I think that as long as you are happy with the smoothness of the shifting and the feel of the clutch, there’s nothing wrong with running generic low-buck 10w-40 oil from Walmart or Autozone. Mobil 1 is a great, high quality oil, but if you change oil frequently, using Mobil (or Bel-Ray, or Klotz) will not provide any noticeable protective benefits. You have to consider the application and a KDX gearbox (as gearboxes go) is not a highly stressed one. Sometimes good enough is more than good. A titanium-alloy spoon won’t let you eat your cereal any more efficiently than the plain old steel one you got at KMART.

Jim Crenca · Oct 23, 2002

BRush,

Conceptualy I'm with you; but if you're time is worth anything, the cost of clutch / gearbox repairs or inspection is a whole lot higher than changing good oil often (I'm assuming that most of us only ride once a week for 50 to 100 miles). Why take a chance hurting a $4,000 bike to save $50 per year? Besides, my bike is my baby, and only the best will do for my baby (within reason) :aj:

RJ-KDX · Oct 23, 2002

I agree with Jim, but with some hesitation. I've got about 350 miles on my current tranny oil. IMO, changing the oil every 100 miles or so is a waste of money, considering the manual recommends changing it at 600 miles.
I try and ride every weekend, and semi-fast (IMO), and I don't recall having any shifting problems. There is such a thing as obsessive compulsive disorder that some people have. Some of you might want to look into this.
Now call me crazy (my wife seems to think so) I like to pamper my bike just like the next guy, but let's not go overboard.
Remember, it's just a machine. :worship: :worship: :worship:

Tom Ludolff · Oct 26, 2002

Castrol Syntek 5w50 full synthetic does not have the EC label either. From what I understand , it should be clutch friendly?? It's about $19 / gallon. That's $4.75 / quart, which is $1.25 / quart cheaper than BelRay semi-synthetic.

Semi synthetic oil vs. regular

Tom Ludolff

kevinkdx

tigerowner

Rich Rohrich

Moderator / BioHazard

Dazza

tigerowner

Dazza

Tom Ludolff

Jim Crenca

tigerowner

BadgerMan

Jim Crenca

BadgerMan

BRush

Jim Crenca

RJ-KDX

Tom Ludolff

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