Here are the pages from the TCH's "New Car Features Guide" covering engine lubrication.

Stan

 

http://www.carbibles.com/engineoil_bible.html

 

Those two site were very informative.

I did not realise the VVT was driven by the oil. Either way, if you loose oil pressure, I am sure the timing of the valves will not be changed to cause an interfeence and catastrophic failure.

also my favorite line from the second site is "Overfilling will mean the crank dips into the oil and churns it into a froth. Froth is good on certain types of coffee but not good in an engine. The mixture of aerated oil will be forced into the bearings and in case you didn't know, air is not a lubricant. Typically this means that bearing damage will follow quite rapidly, especially if you are driving on a motorway. You'll know bearing damage when you get it. The engine smells like a garage mechanic cooking over an open flame and the noise coming from the engine is the sort of thing you'd normally hear in vaudeville plays when a piano is pushed down a flight of stairs."

If you want more data on oil and oil types there is a great post at:

Oil discussion @ Planet Nautique

 

I bought a 2003 Corolla and was excited to get a all aluminum 4-cylinder engine with VVT. I talked to the local toyota tech at the dealer. He told me that toyota was the only one using the hydraulic (oil) method of varying the cam. I asked that same question, what happens if you loose oil pressure to the VVT. He said the timing simply goes back to normal.

This talk about foam in the oil sure brings back memories. In the early 60's the top fuel dragster owners were having fits blowing engines, locking them up with burned bearings. The problem was the unburned nitro getting into the oil and foaming it up. Oil pumps will not pick up foam, only oil as it's designed. They ended up switching to Valvoline oil which seemed to eliminate the problem. They did change oil ever few runs. Nowadays most all engine oil is of top quality, dino or full synthetic.

Todays 7000+ horsepower top fuel engines run a 70 weight synthetic at the NHRA events. The piston to cylinder clearance is much tighter. They now use low friction pistons and rings including a special ring that helps keep the nitro from getting into oil pan.

In the older engines when the crank rotates the rods would throw oil up into the cylinder for lubrication and helps cool the pistons.

Looks like on our hybrid ice, toyota uses 4 sprayers, one for each cylinder. I would think this is a better way to lubricate the cylinders and to cool the pistons. The .pdf said these will shut down if the oil pressure gets low. Thats good toyota engineering.

My wife bought a '77 Corolla. It was a 1.8 hemi head 4-cyl about 85 hp engine. Over the years toyota added computers, fuel injection and a coil over plug ignition. Now that same basic 2002 VVT engine is all aluminum and is up to 135 hp. Our Atkins engines are 147 hp in comparison and have all those same features. I forgot to include the lightweight pistons and low friction rings. The valvetrain is also designed to not physically pull much power from the engine. The cam lobes are skinny, less turning weight, also causing the buckets to be lighter. The valve springs are just strong enough to allow the engine to go to max rpm without any problems.