The '08 1GR-FE in your 4Runner is of the Single VVTi flavor still installed in the current Tacoma and takes 5w-30 oil. The FJ Cruiser & 5th Gen 4Runners starting in '10 use an updated Dual VVTi 1GR-FE with a Canister Style filter that adds roughly an additional quart of oil capacity, these engines take a 0w-20 oil due to their VVTi systems and slightly tighter tolerances.
This is actually mostly correct, the other big factor in the oil is that many of the engines Toyota now makes including the 3UR-FE utilize Dual VVTi. In the switch to a Dual VVTi system Toyota felt a 0w-20 is a better oil to use for its volume flow at a given viscocity.
What many people fail to realize is that it is not pressure that is as important in a modern VVTi system (or cylinder deactivation system) but rather oil volume. I can pressurize a 55 gallon drum to 50psi, or a syringe to 50 psi; they're both 50psi, but the rate at which oil will flow is much different. Think of it as voltage being pressure and current (amperage) being the volume. The VVTi needs both a certain pressure and a certain volume of oil to operate properly. Now factor in that the vehicle needs that volume of oil within a certain time frame or else it won't operate the VVTi accurately and properly. This is why Toyota switched from 5w-30 to 5w-20 in many of their engines and now they recommend only 0w-20 in most of their engines.
Toyota is far more forgiving with their oil specs than other manufactuers to complile specific additive properties in their oils for various needs and failing to meet their strict specifications can and often does damage the engine in the long (and sometimes short term.) For example I had a '10 used GL class Mercedes someone had put the wrong oil in and it threw VVTi codes and the engine ran horribly until we changed the oil. The Chrysler 6.2 Hemis take a different oil (I believe its like a 5w-40 or 15w-40? Something like that) that if you try to use 5w-30 like most Chrysler engines take it will not operate the cylinder deactivation lifter properly and the vehicle develops misfires and in some cases complete dead holes (due to the fact their system operates on oil volume to keep the primary lifter solid and allow the rods to run on the camshaft.)
[MENTION=59117]glocke12[/MENTION]
In short I would kindly inform the technician that he has put the wrong oil in your vehicle and that it needs to be changed to a 0w-20 oil as the Dual VVTi 1GR-FE in your 5th Gen 4Runner has a different oil requirement than the single VVTi 1GR-FE and it could cause issues with oil delivery and VVTi operation.
