Oil Viscosity
 

Turbocharged rotaries have to be one of the most severe environments for engine oil in the world: ungodly fuel dilution, blow-by, extreme heat, and high rpm turbine abuse. Alot of the members here are running 15w-50 to offset some of the fuel dilution issues, but is it really necessary? How is apparent viscosity affected? I'm posting a poll, but would also like to hear from those who have evaluated % fuel dilution and apparent viscosity via UOA...thanks

Not many aspiring Tribologists here I take it ;) I find this topic fascinating (and a little discouraging, because I've never seen an oil look as nasty and thin so fast as it does in an FD)

I'm running Amsoil Racing 20/50.

royal purp/ redline 20-50 w/e is available. every 2k!!

10w30 and I change oil every 1,000 miles.

Ever had it analyzed after a few thousand miles? Would be fascinating to see how it holds up...Amsoil makes a good product, I'm running Mobil 1 15w-50 EP right now

That "dirty" oil is just doing it's job by suspending the soot and junk that causes build up and deposits AKA "sludge". That build up is really detrimental to hydraulic lifters and timing chain tensioners.

Ever change a diesel vehicle's oil? Nastiest stuff you've ever seen, right? Filthy even after the change ... but they can go half a million miles or more with that dirty oil.

If you're sweating what your oil looks like, I wouldn't. Just pre-mix and be done with it. How many 13B's are having bearing failures and how many aren't getting enough seal lubrication?

Bump for UOAs.

I do pre-mix and no I'm not sweating what it looks like, but I do sweat the fuel dilution issue to some extent...past UOAs posted here indicate it can be 3-5% or more, which is crazy

I know Brian (BNR Turbos) said he lost an engine from running dirty oil too long (and it wasn't more than about 4-5k miles if I recall correctly)

although not specific to the FD, this guy shares my philosophy in why it's important to run a high viscosity oil in these engines

http://www.bobistheoilguy.com/forums...76#Post1335676

20-50 here

I've got 4 oil samples waiting to go for analysis. It'll be till the end of the year until I can finish my evaluation.

Dave

x2

Currently Castrol GTX 20-50 running the OMP... Will switch to Mobil 1 20-50 after I go to premix.

I should have included another category for 20w-50, that seems to comprise the majority of the "other"

I'm going to try Amsoil 20w-50 next oil change...for those of you running it, what oil pressures are you seeing when cold? they have to be up there

http://www.mobil.com/USA-English/Lub...cycle_Oils.asp - Mobil 1

http://www.ilacorp.com/images/web_20w50.pdf - Idemitsu

http://www.schaefferoil.com/datapdf/705.pdf - Schaeffer

http://www.amsoil.com/storefront/aro.aspx - Amsoil

http://www.castrol.com/liveassets/bp...tEvoXTra4T.pdf - Castrol

Based off the information from these PDS (product data sheets) imo i can see idemitsu as rotary specific oil because it keeps a high viscosity and flash point. Amsoil is the next best because of its high viscosity and it keeps a high flash point almost equal to that of idemitsu. Mobil one would be my third choice because its the opposite of amsoil it has the highest flash point while keeping a viscosity almost equal to idemitsu. This is only 20w50 oils and i know viscosity and flash points aren't all there is to oil but i figured them to be important especially since this post was asking about viscosity.

This is all IMO the only real way to prove this is with multiple UOAs. heh Which i dont have:icon_no2:

use whatever weight makes you sleep better at night, makes you feel better, have less emotional problems while deciding. just make sure the API rating is SH or better

same here, but use 10w-40. As I'm sure you've read on bobistheoilguy the newer direct injected engines are seeing strong fuel dillution as well and I'm doubting what they're seeing is as much as most rotaries have. I don't feel it's worth it to spend big bucks on a synthetic if I'm not sure that it'll still live up to this issue, and I'm sure as crap not using Amsoil and changing every 1000 miles.

goood thread, even though it's been discussed in the past it's nice to see continued thought put into the subject.

and yes Dave I'm still on the edge of my seat waiting for you to follow thru with your testing!

Here's my oil analysis taken at 1,000 miles on the oil and 4,000 miles on the engine fwiw. My fuel dillution was at 3%. It's the readings to the left.

http://i21.photobucket.com/albums/b3...59415_0001.png

you lost me there, viscosity of Mobil 1 20w-50 is similar to Idemitsu?

you are right its about 10 off :wallbash: :wallbash:

I was just thinking this same thing the other day whilst investigating my oil leak. My oil has MAYBE 1500 miles on it and...yechhhh.
And I have had diesel engines....I think the rotary's looks worse. It just looks...unhealthy or something. Like oil with leukemia....

Castrol GTX, 20w-50. :icon_tup:

14w-40 shell helix for me

Castrol gtx 10w-30 for me.