I'm running Maxima 4 Stroke Premium oil, and seeing the numbers Scooby posted I looked at their website. I found a page which details the numbers compared to what Scooby posted. I'm using the 20w50 - is this TOO thick perhaps? My oil is 193.3 Viscosity cSt @ 40°C - twice what DSJobber is running & even more than the Scoob-meister. Am I loosing a little power due to thick oil?

Color D 1500 Green Green Green
Gravity °A.P.I. 31.4 30.4 29.5
Viscosity SUS @ 100°F 375 575 1008
Viscosity SUS @ 210°F 64.9 79.2 104.5
Viscosity cSt @ 40°C 73.33 111.6 193.3
Viscosity cSt @ 100°C 11.31 14.92 20.79
Pour Point, °F -20 -20 -5
Flash Point, °F 390 425 480
Fire Point, °F 200 460 515
Viscosity Index 146 139 127
SAE Viscosity 5w30 10w40 20w50


http://www.maximausa.com/products/4s...um4premium.asp

 

I also found a link to someone who took a LOT of time researching oil, I thought I got the link from the forum, but if not, you all need it. If you've all seen the link before, then don't bother reading it.

http://motorcycleinfo.calsci.com/Oils1.html

Also this link which has more info about the ratings:

http://motorcycleinfo.calsci.com/API.html

In the long winded article on the first link, we learn that Synthetic oil, is not actually synthetic anymore. Synthetic oil is now just a higher rating of oil, and can be made from dinosaurs, but it has to be the better ones at least.

 

I can't say for sure what oil pressure the motor sees. I have an orifice at the oil pressure sender port that drops oil pressure down just for the turbo oil feed (maybe 10psi drop). This is where I have the gauge, so it reads a little lower than what the motor sees. I was seeing readings struggling to reach 20psi @ any RPM on the non-fresh Klotz and around low 20's with fresh Klotz. With Mobil 1 20W50 VTWIN, the pressure when hot was between 40-60psi, from idle to full throttle.

I haven't had big-end bearing problems. I haven't had to change any case bearings. One broken crank so far, no problems since.

 

I just checked the viscosity specs @ 40C for Klotz 20W50

Klotz 20W50 = 160.0 cSt @ 40C (this is fine)

Klotz 15W50 MX4 = 100.0 cSt @ 40C (this is not fine)

 

I switched oils from Golden Spectro to Valvoline ATV 4 stroke and almost the same results with the low oil pressure. It is warm almost all year round here in So Cal. Would switching to 20-50 solve the problem?

 

I don't have the viscosity specs on the Valvoline ATV 4 stroke 10W40, but I'd guess that it has the same low viscosity as the spectro 4 non-synthetic you were running.

If you try 20W50 Mobil 1 V-TWIN, you shouldn't have low pressure anymore if the motor is good. The V-TWIN oil is very temperature stable also, so the pressure will be maintained at temperature and the motor will run cool.

You don't need 20W50, I recommend either 10W40 or 20W50 oil that has a viscosity spec of 130 cSt or higher at 40C. There are 10W40 oils that meet this. But your climate probably warrants 20W50.

 

Amsoil 4 stroke