http://www.api.org/~/media/files/certification/engine-oil-diesel/forms/whats-new/9-dap-understanding-lubricant-requirements-of-hybrid-electric-vehicles-dclarke-infineum-usa.pdf sorry if this was posted before. it's news to me.
Good data but I hoping Infineum would interpret it more. Are we talking synthetic or dino oil here for the Prius: ILSAC GF-4 SAE 5W-30 What are they saying about CAMRY MPG? If I undertsand, they tried a really low viscosity oil, and the dashboard MFD read-out did not show a MPG benefit, but the data logger showed a huge MPG benefit? Are we saying the data logger is the true data?
Not a very scientific study. A single-car sample. All kind of outliers possible - what if something was wrong with 400-K miles Prius PCV or breather tube? Or spark plugs? Or thermostat? That would explain the varnishing. Still, thanks for posting. I think it shows current level of understanding of how oil works in hybrids - Alex
you are right, it was not a scientific study. sorry if i misled you. i did find it interesting how the prius insides looked after 400,000 miles of driving.
Doesn't speak of what brand of oil used either. I'm presuming they used the average OTC synthetic motor oil recommended for the engine and not some of the brands that do a better job at cleaning out gum and varnish accumulation.
Scientific or not, it makes sense that a hybrid engine, or any automobile engine with start/stop technology, will be more prone to accumulate deposits due more time run at less than full operating temperature. Thanks for posting this information.
To me your statement is not obvious. I have read multiple studies that show increased sludge and deposits forming in "hot" engines. Thickening polymers, used in multi- viscosity oils, are unstable at high temperatures. To me it makes sence that cooler, part time engine would have less deposits when all else is equal. Alex
All engines have this problem. That's why oils often have detergents added. Not to start an "oil war," but that's why I use AMSOIL. It's designed to use engine heat to clean the engine of gum and varnish, and when I did a valve clearance check on my motorcycle, it was SPOTLESS on the inside. Not sure if the Prius engine gets enough use to get the same cleaning effect, but if I ever have to have an ICE compartment opened where oil flows, I'm going to want to take a look to see how clean it is.
There's some truth in both sides of that argument; both too hot AND too cool (like short winter trips) are hard on oil.
You will find that anything AMSOIL has all the other brand name oils have as well. Price and availability is better also..
Sugar. <rim-shot> Actually there are technical issues with oil discussions that sad to say too often strays from empirical to opinion. If folks start with oil analysis and some sort of metrics, it is relatively safe. The problem is too often brands make claims not necessarily verified by experiments. It costs ~$20-25 do to an oil analysis. My interest has been in the transmission because it is a relatively benign and controlled environment. Furthermore, sources from other Prius have helped us form a reasonable understanding of what is going on. I just don't see that degree of disciplined investigation of engine oil. It is what I call a 'hard problem' because I can't figure out a reasonable approach that would work. Bob Wilson
