Originally Posted By: JoeFromPA
Frank - I found it interesting that you linked suitable viscosity with engine RPM usage in this passage, "Right now, today, I believe the best 30 grade oil is Valvoline full synthetic MaxLife. It has a 100C cSt of 11.7(kinda low for a 1500-1700 rpm engine but would work in the Cavalier which often see 1800-2000 RPM) It has a HTHS of 3.6, that is good even for the Silverado engine."
So by your logic, someone like me whose engine regularly sees 4000-5000 rpms (2006 Civic SI) and cruises at 3500-4000 rpms regularly, a Xw30 would be perfectly suitable?
Joe
P.s. You've actually given me alot to think about in regards to running a 5w50 in my LGT during the summer.
I will try to answer your question in a way that I hope you understand. My explanations are not always crystal clear.
I also suggest you do a search on Molakule and Doug Hillary. Search for them under HDEO also. Do a Google on lubrication engineering and a Yahoo on tribology.
I am going to assume(yeah, I know) that your engine runs at "high" RPM but not at high load. By that I mean you never lug the engine, you know how and when to shift or have an automatic transmission. You never load the engine by pulling a camper, haul rocks, and like. When you do load the engine, it is because you drag race from traffic lights, take it to red line passing that fool in front of you, and just enjoying a high rev engine.
(I had a bike that was very sweet at 10,000 RPM and would play with 12,000)
You also have a very good, well designed, pressurized lubrication system. This pressure system delivers, even in a worse case scenario, adequate oil volume to your bearing/journal. This volume means more oil flow, more exchange, therefore cooler oil, which means the oil doesn't thin as much in the bearing/journal. Now, the lubricant film, and wedge, doesn't depend to such a greater degree on the pumping action of the rotating journal alone. Add to this the fact that your journal "IS" operating at a peripheral velocity that pumps very well. This gives you good oil flow, good oil film, good oil wedge, good lubrication.
Now, the main problems you have to worry about is load and hot spots. HTHS, Friction Modifiers, Anti Wear agents help here. Full synthetic addresses hot spots to a greater degree. I PERSONALLY LIKE AN HTHS OF 3.5+ AND ACTUALLY USE A HTHS OF 4.5. Is that overkill? You bet your bippy it is.
Quote:
So by your logic, someone like me whose engine regularly sees 4000-5000 rpms (2006 Civic SI) and cruises at 3500-4000 rpms regularly, a Xw30 would be perfectly suitable?
The answer is yes, BUT IT IS NOT BY MY LOGIC. This is where you need to do the search for posts by Molakule, Doug Hillary, and Google for lubrication engineering, Yahoo for tribology. I have used 15W-50 in a Mitsubishi I4, KIA I4, Dae Woo I4, all higher RPM engines and with outstanding results. Overkill, probably. I used it in my daughter's Camaro which would see 3,500 RPM, but not often.(I hope)
I no longer pull a trailer because arthur won't let me back it up well enough and my wife doesn't like to drive with it.
We came up with a full camper pack for our Silverado. When I have that pack, my wife, grand kids, crossing the Great Smokey Mts from Maggie Valley to Cherokee and then Cherokee to Gatlinburg, in tow/haul mode, pulling 1600 up to 2000, oil gets hot. I have enough cSt, HTHS, too keep the bearings happy. It has kept the bearings happy in my old pickup for 301,000 miles with camper pack and trailer, and it has made that trip dozens of times, and it is still a daily driver. Could use a coat of paint and about 25 pounds of bondo.
MY WAY IS BY NO MEANS THE ONLY WAY. Based upon 45 years of getting to break in new engines and take them to trade/sell, getting to talk to an engine design engineer, getting to talk to tribologist and inter-net communicate with tribologist, having a close friend that is a professor of chemistry, the temperature/terrain where I drive and where I drive to, the use of my vehicles, and more convince me that mine is is the best way FOR ME.
