This is a simple case where bigger is NOT better. Regardless of what anybody tells you; higher weight oil will not provide better protection, even under extreme conditions. If you use a higher weight oil, then recommended, you are reducing the efficiency of the system. There are many advantages in using the lowest recommended viscosity motor oil. The most important is at start up. Up to 80% of engine wear occurs when you first start your engine. This is not only when it is cold. The lower the weight the faster the oil reaches the vital parts of your engine (cold pour rate). If you take the time and look at the oil manufactures specs and UOAs on the different weight oils you will see that there is very little difference between quality synthetic 20/30/40 weight oils but there is a noticeable difference in pour rates. The best protection is provided by the lowest recommended viscosity. You will also find that any 0 weight oil (0w-20/0w-30) is usually one of the highest quality synthetic oils that manufacture makes. I personally use Amsoil 0w-20 but if 0w-30 makes you feel better the differences are minuet. The 0w-20 has a little better pour rate. You can safely use any 0w-20, 0w-30, 5w-20, 5w-30 or 10w-30 oils. The synthetics are of course better and will last longer but even conventional will provide safe protection for 5 to 10K miles. The break-in oil has shown to last 10K miles.

Why would you use higher then 30w oil when it provides less protection. The high viscosity number represents the size of the molecules needed to protect the engine at operating temperature. If the engine was designed and engineered to run with 20/30w oil, 40w molecules may not even be able to enter the tight clearances of the engine. Believe it or not the Toyota engineers know what they are doing and they recommend what's best for their engines.

Koz

 

Thats weird, I actually gain so much more mpg . Half way mark I used to get 120miles, im at 150 (18.8-19mpg on the cpu) right now and I was pushing it a couple of times. I just got my oil change like 1k ago, is it okay to run it about another 2-3k before i switch it out? Im not into technical stuff so plase help =D.

 

Interesting thread.

I was going to have my 5K service when I pull it out of storage next month and switch to synthetic; so given this, I should tell the service department to use 5w-20 or a 0w-20 - or does it matter...? I would assume that service is going to put in 5w-30 since no-one seems to be aware of the TSB on this issue.

 

I was planning on switching to 5-20 mobil 1 syn. on my next oil change but after reading a few threads were people are running a 5-30 synthetic due to summer temps and stop and go traffic. (i'm located in the central valley) I will probally go with mobil 1 5-30 synthetic on my next oil change..

 

Humm right now im getting 19ish mpg. I used to get around 20-21 mpg.

My guess is it should be ok to run another 2-3k miles before switching it out. But then again i would probably get flamed for saying that.

 

kikaida, i use 5-30w royal purple. I know everyone here says 5-20w due to the tsb, but on my next oil change i'll still use 5-30w. I myself wouldnt use 40w in our cars.

btw: you comming out this sat?

 

Hey llamaboiz, thanks for the heads up. If you say 40 is no good. Then 40 is no good.

Sat? where at? Ah i know..check the Hawaii Forums?

EDIT: lol nvmd its on your sig

 

Koz,
Im ordering a case of 0w-20 from Amsoil. Do you run the amsoil ea filter or use the oem?

I run Amsoil in my 4Runner with the Amsoil EA filter and change the oil every six months, but not sure about extending the drain intervals with the IS.

 

No you won't get flamed. I would recommend running what you have until it's time to change it unless gas goes to $20 a gallon sometime before you change. I just wouldn't run 40 weight because it's not doing anything good for your IS. Changing it prematurely is just as big a waste.

 

The Ea oil filter is not available for the IS, I use the OEM.

I also have a V8 4Runner but I'm using the dual bypass system with the Ea filters. I have 36K miles on the 0w-30. If I have to change the oil I will go to the 0w-20.

Koz