which oil will make my 520sx purr?

I use Torco MPZ full synthetic at the moment. After I go through this next case, however, I'm going to try some blended synthetic to try to get away from the gnarly cold clutch noise. Once the motor is hot the synthetic is fine and there is no doubt that it's good for the bearings and gears. Change it often no matter what you get. Congrats on the new bike, you won't be dissappointed.

ANY synthetic that meets the specs in the owners manual will be fine. Just find the one that meets your needs (cost, availability, color? whatever):)

Here's a quote from a reputable KTM dealer. I won't use the business name as I don't have permission to:
We attended a KTM factory trained seminar for
the RFS motor. They specifically said a full synthetic oil was not needed or
recommended & could cause the clutch to slip. We've used Bel-Ray
semi-synthetic since day one with great results.

A lot of people are using many different oils, including synthetic, with no
problems.

I also use the Belray EXP semi-synthetic in my bike. In the August Dirt Bike or Dirt Rider, I can never remember, on page 68, KTM's Tom Moen is dumping Spectro 4 straight dino oil in an RFS.

I've used Motorex full sythetic in my bike since it was brand new. I'm a clutch abuser, but haven't had any problems with slippage at all. I'm still on the stock clutch.

I ran Redline synthetic in my 380 for 2 years with no problems and it still had the stock (with a 280 lb guy and lots of abuse) clutch in it when I sold it.

I started off using Torco 5/50 in my Berg. I have since made the switch (thanks Strick) to Mobil 1 15/50 synthetic. I have zero complaints with the Mobil 1. I can now afford to change it twice as much because it is 1/2 the price.

I am now changing my oil every 2 rides and the filter every 4 rides.

With all the new trick 4 strokes out ,this is going to become like what premix do you use .

All I can do is give some feedback on what works for me
I use DUMONDE YAP400 it is a blend specifically designed for four strokes that use the same oil for the engin and transmission (developed for endurance road racing) I started using it in an XR 440 that ate a clutch every ride and the trany shifted like a box ovf rocks . It was like magic in my 440 I stoped loosing clutches and the trany that I just new I was going to have to replace 4th geer started shifting like new. I sold my XR440 to a friend two years ago he still runs the yap 400 and is still on the same clutch .

so with the new ride 520exc i have just stayed with the DUMONDE YAP400 .
they also have a brake inn oil just for four strokes .
Good luck and change often


2000 520exc
2000 380exc
winner 2001 Funkey Chicken NHS open x
on the 520 thanks ETRA