IF..... Most engine wear occurrs during startup (i.e. cold start), and the Prius engine starts and stops numerous times during the typical excursion, would this engine be subject to premature wear?? I am hoping that the fact that these are warm starts and that there should be some oil on the surfaces makes a difference. If not, there is always my 7 year/ 100,000 mi warranty. Bill Almost 200 miles on my new Prius
Using a traditional design, that would indeed be true. But the hybrid system doesn't. Instead, it uses a design that dramatically reduces wear... which is why the starts are so much smoother in Prius than in your previous vehicle. The motor is far more powerful. RPM is much faster. Engine components are lighter weight. And startup doesn't actually occur until oil pressure is established.
<div class='quotetop'>QUOTE(bumblbe @ Mar 8 2007, 05:18 PM) [snapback]402530[/snapback]</div> Well, so far there doesn't seem to be evidence of excisive wear on the Prii that have gone more than 100k miles. I believe there's a feature that spins the engine at times when it doesn't actually have to run. I think (there are people here that know for sure, but I usually put in my 2 cents) that is partially for lubrication. In any case, I wouldn't worry. Just be sure you make your oil changes. Dave M.
If I understand correctly, Toyota has at least partially mitigated this in at least two respects: 1. When the engine starts, it is not started in the same manner as a "normal" engine. The engine is quickly spun up to 1000 rpm by MG1 before the fuel and ignition are enabled. This means that the oil pump is also up to speed and is pumping the oil to the running parts before ignition. 2. Toyota added a "thermos" bottle to store warm coolent after shutdown so it can be circulated at the next cold start. This should reduce the amount of time it takes for the engine to fully warm up. This was done primarily for emissions reduction, but it should also help improve engine life.
<div class='quotetop'>QUOTE(bumblbe @ Mar 8 2007, 05:18 PM) [snapback]402530[/snapback]</div> You hit the nail on the head with - "(i.e. cold start)". When the engine is "cold" as in it has not run for some time; the oil drains drains back to the oil pan. Consequently when a engine is started cold there is very little lubricant (oil) between the moving surfaces. Consequently increased engine wear results. Also when an engine is cold, clearances between moving parts is different than when the engine is warm. Again, increased engine wear results when cold. During normal operation, the Prius does not have enough time to radically cool or drain a significant amount of oil, consequently this type of wear should not be an issue. Keith
<div class='quotetop'>QUOTE(Tech_Guy @ Mar 8 2007, 07:50 PM) [snapback]402545[/snapback]</div> Remember that MG1 briefly spins the ICE before the computer orders up fuel and spark. In effect, MG1 is also taking on the role of a traditional starter and a de facto pre-oiler. Pre-oiling is standard on no passenger vehicle I'm aware of (except to the extent it's "built-in" to HSD vehicles), though you can add it via kits (Amsoil has one, for example) for several hundred dollars.
This is also why those of us who live in cold climates, and don't have heated garages for our cars prefer full synthetic oil. It stays more fluid on extremely cold mornings, and gets to where it is needed faster than conventional oils. I believe the extra wear is for "cold starts," not warm re-starts. Again, momentary lack of lubrication is a likely culprit due to thickened oil not reaching bearings and other surfaces immediately. In warm restarts, the surfaces already have plenty of oil. Harry
<div class='quotetop'>QUOTE(ekpolk @ Mar 8 2007, 06:05 PM) [snapback]402554[/snapback]</div> The engineers at Toyota really spent a lot of time designing this vehicle. The function that you describe will certainly reduce some of the wear associated with start-up. Now, I just wish they would forget about lithium-ion batteries and come up with a small, safe thermo-nuclear battery that would eliminate the need for gas, or plug-in. Oh well, just dreaming... Keith
<div class='quotetop'>QUOTE(Tech_Guy @ Mar 8 2007, 11:18 PM) [snapback]402612[/snapback]</div> LOL I saw this and had a brief flash of a crash between one of these and a hydrogen powered car. POOF!
I just recently got my first oil analysis back from Blackstone Labs for my Prius. After 11 months and 3100 miles (13,100 total at oil change), I received a clean bill of health. The 11 months included four months of sitting while I was deployed all summer, then a ridiculously cold Alaska winter. I use Mobil 1 5-30. Blackstone made note that my engine is now past the break-in point and they expect the very small amount of wear that was occurring would improve even more as time goes on. Despite the extremely long oil change interval and nearly 100% city driving, the oil pH was still very good and the metals concentrations were low. Oil and air filters (OEM) were doing well. I was told to extend the interval to the factory-recommended 5000 miles, despite the time.
<div class='quotetop'>QUOTE(Boxster...WRX...Prius? @ Apr 23 2007, 11:46 PM) [snapback]428896[/snapback]</div> Beggin your pardon, but oil pH is not measured. Total base number (TBN) is a measure of the capacity of the oil to neutralize acids from combustion, though. It is a $10 add-on at Blackstone Labs. I would certainly agree that your analyses (posted in the other thread) indicate a happy engine.
