MotoXRacer_19 Posted February 4, 2018 (edited) Hi guys, probably a stupid question here, but I figure you can never be too safe. I have some Motorex 15w-50 from my 2010 KTM 250 XC (which I sold) and I was wondering if it would be okay to run in my 2014 KTM 350 XC-F which calls for Motorex 10w-50? What would be the side effects of running a 15w-50 instead of a 10w-50? Also, if you have any suggestions of good oil to run, please feel free to recommend it and give your reasons why. Thanks guys. (Attached is my 350) Edited February 4, 2018 by MotoXRacer_19 Share this post Link to post Share on other sites
Decreasing Dave My Ride Posted February 4, 2018 (edited) Beautiful bike, congrats. The first number is the viscosity at cold start, 10 is thinner than 15. The second number is the viscosity index at operating temps, so at temp 50 = 50 = the same. A 10w-50 will flow better than a 15w-50 at initial start up, however both should flow equally at engine operating temperature. The only reason that I would caution running the 15w-50 over the 10w-50 is if you plan on starting the bike during this winter time weather and jumping on and riding right away without a warm up time (This is not recommended at any time of the year with any oil). It may not do any damage at all, but it will not flow as easy until it reaches closer to operating temperatures comparatively. Dave Edited February 4, 2018 by Decreasing Dave Share this post Link to post Share on other sites
Paolo_k Posted February 4, 2018 Use it in summertime and enjoy! Share this post Link to post Share on other sites
Bluechain Posted February 6, 2018 Use it and enjoy, Rotella T is what I have been using for years... Share this post Link to post Share on other sites
Dirtshark808 Posted February 6, 2018 I use Maxima pro plus fully synthetic 10w50 and it's working really well. I ust to run Rotella and I was having clutch issues. The Maxima oil is really easy for me because my bike uses 1liter so 1 bottle per oil change. Haven't had any clutch issues since switching. Share this post Link to post Share on other sites
mbrick Posted February 21, 2018 (edited) As others already covered, 15w is just thicker when cold. Don't use it when it is cold out, or warm up the bike in the garage? With the cams being journal bearings, and some reported failures out there with that plastic breather tube, I would blend the 15w-50 into your truck or something else, and buy the correct viscosity for the 350. I bought this case of 10w50 when it was on sale for $35 (seems to be every few months), but it's still not that expensive. https://www.amazon.com/gp/product/B008MISF54/ Edited February 21, 2018 by mbrick Share this post Link to post Share on other sites
