I mentioned in message 304 that I had a concern with the number of times the gas engine started and stopped in my test drive of the Prius. It is my understanding that engine startup is the time when engines experience 20% of their wear.<br><br>What has Toyota done to resolve the problem of excessive engine wear at startup on the Prius?

I will get you a complete and technical response tomorrow. I did dialogue with the exec eng. last week on this subject but I've been recharging my batteries on vacation the last week so I don't want to quote you any inaccurate tech. <br>But if my memory serves me, the motor/generator (I'll verify if its #1 or 2) will spin the engine to about 1300 rpm before injection of the gas/oxygen mix - then compression and rpms are increased. So as I understand it priming the engine to the rpm level before ignition lubes the system (like cranking the engine with a starter). Additionally, this eng has been modified significantly over a conventional. Since it won't see the high rpms (not in excess of 4500)the engineers were able to develop it with lighter weight components.<br>We do not expect any decreased durability in the Prius IC engine vs any other Toyota product. It carries the same 5 yr/60K mile powertrain warranty as any other Toyota product. We could never badge it a Toyota and sell it if it didn't embody and represent those characteristics which consumers have come to associate with the brand - Quality, Dependability, Reliability and Value. <br>Not a commercial. Typically the car is the third largest acquisition that consumers will make behind their mortage and child(ren)'s education. It better be right.<br>Just like the info that I share with this club.<br>So I will confirm the accuracy of my response with you tomorrow.<br>Participants have given me a few things to respond to and clarify in the last week (even my field personnel).....PM

I appreciate the reply and your investigation. I hoped you enjoyed your short vacation.<br><br>I still have a concern even with your preliminary explanation. Priming the system does not eliminate the wear at initial engin turn over. This is where the significant wear factor comes in.<br><br>Making the engine components lighter may have some effect, but the metal on metal contact at intial turn over without oil pressure, is still there. Forgive my ignorance, but unless some exotic oil impregnated bearing components have been used, start up wear is still a significant factor.<br><br>60K miles is not much for the engines today. 150K+++ seems to be the rule. Under the worst circumstances, most modern engins will last 60K miles. Failure at less than 100K is not an acceptable probability.<br><br>Thanks for the time you have already spent answering questions on this forum. Your expertise and candidness is greatly appreciated.

Priusman passed this one to me also.<br><br>Most engine wear occurs during start-up as you note, cold starts worse than hot starts. Much of that wear is due to high loads on unlubed parts.<br> <br>Prius uses the generator to start the engine in a slightly different manner than conventional ICE vehicles. In Prius the engine is cranked to 800-1000 rpm before fuel and spark are applied. This reduces the load on the bearings and piston/cylinder by not starting combustion until oil pressure is established. With no combustion the loads are quite small. There is a residual oil film on all surfaces from previous operation.<br><br>In an ordinary vehicle spark and fuel are added immediately on crank and cranking speed is usually less than 100 rpm. Wear is made worse if fuel washs the lube from the cylinder walls.<br><br>Prius has been extensively tested and we are confident that the durability experience will be positive. As Priusman notes Toyota made is name for reliability and we don't plan to change that with this new product.

The tech cavalry has arrived.<br><br>For all you participants, ee is my alter-ego and partner in crime.<br><br>What I clarify in marketing, distribution, operations and sales as the Program Manager,.... ee is the source of technical expertise for Prius in North America.<br><br>welcome to the club ee, I still promise to call.<br><br>PM

ee of ee,<br><br>Thanks for the technical explaination about what happens during engine start. How about the use of synthetic oil? If one is trying to eek out a few more mpg and to minimize wear during the many engine starts, synthetic oil seems perfect. Does Toyota have a position on the use of synthetic oil in the Prius?