Me, too, db. All I know is in various places when snooping on the web, it has been stated that the variable valve timing needs a certain weight oil for proper operation. So, how does one find out for sure?
I know a man who lived in UAE for 2 years. He certainly did not drive Lexus at all. But, he adapted to the heat, and used to run in the sun for two hours well over 120 degrees. When he visited us in McAllen, he went out for a two hour run in the sun. It was only 95 degrees and he was upset because he couldn’t even work up a sweat.
He said it took him 3 months to adapt to the heat. We don’t visit McA that often nor for that long, so the heat is hard on us. he said it would take me six months to adapt, at my age.
I did work with environmental chambers in my work. I think a car cooling system is designed for a certain amount of temperature difference, and if it isn’t there, heat transfer will be reduced, and he engine will run somewhat hotter. Tom McCahill used to make negative remarks about how hot American cars ran in the summer.
Also, from non-related temperature work, I do not think that heat transfer is linear with a varying temperature difference.
No, actually, I am sure the heat transfer is not linear with changing temperature. We would put thermocouples in various places in our products, and record the temperature over chamber emperature range. As the box cooled, the change in temp slowed to a crawl. What is that curve called? Either geometric or logarithmic? But, a very sharp curve.
For other comments, I have no access to major repair services nor dealers. Most mechanics are self-taught, which mostly means non-taught. The best ones studied at the factory and were taught by the manufacturer. There aren’t many of them. They don’t have tech schools like that, at least not in the degree we do in the USA. And, books of any kind are scarce and horribly expensive.
Even the city mechanics here do not have a simple code reader. The garbage pickup showed -30 degrees engine temp when warmed up. And, a failure which seems to indicate valves out of sync with crankshaft. Their solution was to get rid of the driver who complained about it and put in another man.
It is more than just the valve operation. Someone has said that the new engines are made to very tight tolerances and there are places in the motor where heavy oil will simply not be an adequate lubrication.
Yeah, we need a rich guy to buy a bunch of Lexus and run them around with 25W-50. Hee, hee.
Note: strictly coincidence that two of us referred to McCahill at the same time with crossed posting.