Mobil 1, although a true 5W-30 tends to be on the thin side of the scale. As a result, oil pressure will be lower with a thinner oil than with a thicker grade. Look what happens when oil gets hot and thins out accordingly, oil pressure goes down.
This also may contribute to the louder valve noise. There is less dampening effect with the lighter oil. I have heard this mentioned on BTOG (Bob's the Oil Guy) site where oil is discussed intimately.
I currently have a blend of Mobil 1 5W-30 and Mobil Clean 5000 in my 4.0 engine at 4000 miles and don't notice a sever ticking. My next change will be pure Mobil 1 and a new evaluation will take place at that time.
My service manager said that Toyota does not endorse synthetic oil. This does not mean it says you shouldn't use it, just that they have not put in writing that you should use it. I think they are concerned with 12-15000 mile oil changes that, as we know, are taboo in for the warranty. They may be a bit gun shy because of the sludge problem they faced some time ago in the smaller V-6 engines they had.
This also may contribute to the louder valve noise. There is less dampening effect with the lighter oil. I have heard this mentioned on BTOG (Bob's the Oil Guy) site where oil is discussed intimately.
I currently have a blend of Mobil 1 5W-30 and Mobil Clean 5000 in my 4.0 engine at 4000 miles and don't notice a sever ticking. My next change will be pure Mobil 1 and a new evaluation will take place at that time.
My service manager said that Toyota does not endorse synthetic oil. This does not mean it says you shouldn't use it, just that they have not put in writing that you should use it. I think they are concerned with 12-15000 mile oil changes that, as we know, are taboo in for the warranty. They may be a bit gun shy because of the sludge problem they faced some time ago in the smaller V-6 engines they had.