Originally Posted By: ekpolk
Originally Posted By: Silber Igel
I've been a fan of synthetic oils since the 1970s. I use it in every vehicle.
However, I've agonized for nine months on whether, or not, to use full synthetic oil in our 09 Cammy Hybrid. I did an O/C at 1000 miles to synthetic and now its got M1 5W-20 AFE in it at 7800 miles. At the next O/C, I'm going back to a conventional or maybe a 'blend' at 8000 miles. There's no need for full synthetic in these engines.
Thanks to the BITOG-0-SPHERE; suggestions from new friends here, a chat with an oil analysis company, and some home testing, I'm convinced that either a conventional (dino) or synthetic blend is perfectly adequate.
First, these engines use an Atkinson cycle. They are of very modest output and turn low rpms. (Think of them as running a generator.) They just don't develop the high sustained oil temperatures found in an Otto cycle engine. On a 100F day and a high speed run of some 65 miles, the oil temp in my HYCAM didn't get above 152F. So you don't need the high temp protection of a synthetic.
IMHO, the lower oil temps mean the oil is almost always somewhere between it's "W" rating and highest viscosity rating all the time, so you need a low viscosity oil for the best flow and good MPG.
Second, the engine has a mind of its own. A hybrid motor cycles on and off as it needs to. Lots of starts and lots of stops compared to a conventional set up. So there's probably a 'cold/warm start' wear issue vs. a conventional car. Here a 0W or 5W-20 would be the better choice. Again, there are plenty of conventional oils that are spec'd at 5W-20.
You can get 0W-20 oils in a synthetic 'blend' if you need very low temperature protection, but they probably aren't necessary unless you are looking for slightly better MPG.
As long as the oil is rated "SM" you should be just fine with a conventional 5W-20 oil or a 0W / 5W-20 blend. (Which is, oddly enough, what the manual and oil cap specify)
Cheers!
Eagle:
I see nothing wrong in any of that. I would only add this. But first, for perspective, I got my 09 Camry Hybrid "used" last August, with just over 5k miles on the odo. It how has over 29k on it, and I'm in the middle of an experiment in which I'm using the 12+ cSt green GC, instead of the primarily recommended 20 wt oils (remember, there's that odd language in the manual that allows the use of thicker oils).
Using my laser temperature measurement device (looks like a toy handgun, sort of...), I'm consistently getting readings from 175 - 185F off the bottom of the oil pan immediately after shut down. Thus, at least in my car, I think that the oil is running hotter than the 150-160 you're seeing. Could be differences in operations, or perhaps measurement methods.
At any rate, even at the temps I'm seeing, I don't think that there's any problem with the 20 wt oils. I plan to do UOAs on the presently installed GC, and the PP 0w-20 I'm going to use next. I'm expecting similar results. We'll see.
For my curiosity, how are you measuring oil temps? I'd like to see if I can replicate your results.
Hi Mr. Polk ... or is it Colonel???
I take the OT reading off the tip of the dip stick as soon as I can get the hood open. I use the same IR tool. Agreed, I'd not get very worked up with OTs in this range. If you are reading the outside of the pan, you may be getting some heat reflected from the road surface to the outside of the pan.??
As you know, I'm running the
5W-20 M1right now but its due an OC about 2K miles. I'm going pull a sample and send it in for analysis for grins.
Atkinson engines remind me of the old steam and oil engines that are their heritage. Efficient, big bore, short intake & long power stroke, slow RPM jobs that just thump out modest power all day long.
While pondering the use of conventional or blended oil, it comes to my mind that maybe the geniuses at the TOY company designed the Atkinson engine with very low friction piston rings to improve efficiency and MPG. A syn oil or blend might not be our best choice. They may have specifically engineered the rings to seal better using a conventional SM 0W/5W-20 "dino" oil. I raise this question as my neighbor claims he's getting several more MPG (always in the low 40s) vs. mine that gets about 38 - 40 and claims not to use 'whatever the dealer puts in..."
Any thoughts??
Also, the OEM oil appeared to cling to the dip stick in a sticky viscous warm 'caramel' topping manner. The syns appear to be more runny like your nose in winter.
Igel (the hedgehog)