quote:I'm curious too. I will assume for now that friction modifiers are for CAFE and reduce the film strength of the oil and thus reduce the oil's ability to protect bearings.
Originally posted by moribundman: Still, what's with the lower amount,or lack of, friction modfiers in oils for diesel engines? What's the reason behind that?
quote:Like Doug touched on, cam lobes in a diesel engine are placed under extreme pressures during operation, and having a lubricant that can protect properly is absolutely vital to long life and proper operation. For instance, just the other day, I witnessed with my own two eyes a late model Volvo day cab with a ISM Cummins come in to the shop...upon teardown, the cams, for lack of a better word, were "flaking" apart..lobes were literally falling to pieces. Exact cause is unknown, but I can easily tell you the owner or maintenace dep. was not taking very good care of the lubrication needs of this engine...entire top end of engine was coated in a black varnish and coated with a high level of soot. Older engines could get away with lower quality oils and less than ideal mainteance practices, but like I mentioned, modern engines exert such high pressures on cam lobes that a high quality oil with a great barrier/extreme pressure additive package is gonna be required. With that said, I firmly believe, that based upon intended usage, an HDEO synthetic can protect cam lobes better than a PCEO synthetic oil. I don't care much for friction-modified oils unless I'm trying to acheive maximum fuel efficiency levels, but I'd much rather have MAXIMUM WEAR PROTECTION than maximum fuel economy...but that's a whole other discussion. Like I've said, HDEO's are meant to put up with exteme camshaft lobe pressures, and thus the additive package is designed to tackle this challenge, so I'd easily say that an HDEO will offer lower lobe wear levels, but because they aren't heavily GF-3 friction modified like modern passenger car oils of lighter viscosities, you'll be exchanging higher levels of protection for a small, and most likely unnoticable drop in fuel economy. Sorry if I repeated myself too much... BTW, I don't know if I can make this more clear: Only reason for friction modifiers = fuel economy That's the only reason (IMHO)... [ February 21, 2004, 01:49 AM: Message edited by: Jelly ]
Originally posted by moribundman: In a gas engine, will a diesel-rated oil lead to an increase or a decrease in cam lobe and valve lifter wear compared to a friction-modified synthetic that was desigend for gas engines? What about the reduced amount, or lack of, friction modifiers in diesel-rated oil?
quote:Depends. The LS1 and the new truck Vortec motors use roller lifters. That doesn't seem to prevent the CLACK CLACK CLACK noise though. The CI-4 reformulation appears to have thickened HDEO's quite a bit, so their cold temp use is now suspect in senstive motors. Some HDEO's, like Esso XD-3 0W-40, are still quite good in temps colder than -30 F. In a moderate climate, HDEO year-round are fine. Jerry
Originally posted by cousincletus: Don't most gas engines have roller lifters? I don't think the friction modifiers would cause any noticeable decrease in engine life. However, I also like HDEOs and would have no problem using in a gas any engine, as long as the temp isn't extremely cold. Here in Central VA, fleets can use HDEOs in gas engines year round
quote:Thanks! BITOG is a great place to pick up tips on oil-related issues. The best thing for us as a group to do is share our own misadventures, caveats, and tips. For example, in an older Cat 3406B motor, the oil pump is gear driven off the front. If you attempt to use a regular 15W-40 in temps colder than -25 F, you WILL shear the oil pump drive. This will result in no oil pressure and you'll go boo-hoo-HOO when the motor blows up. Of course, it "cost too much" to run a good synthetic in that extreme cold temp. Jerry
Originally posted by Jelly: Jerry, I just want to say thank you for sharing your knowledge regarding HDEO's with us and taking the time to type out these fact-filled, well-written, detailed replies!
quote:It totally second that! Doug, there are no VW oil specs on the approved list for the M1 5W-40, but after all I've read, I'm confident this oil meets and probably surpasses VW requirements. [ February 21, 2004, 04:29 PM: Message edited by: moribundman ]
Jerry, I just want to say thank you for sharing your knowledge regarding HDEO's with us and taking the time to type out these fact-filled, well-written, detailed replies!