Mobil 1 0W-40 in a 1GR-FE

I've got an 06 Taco with close to 200,000 miles and I plan on doing some fairly heavy towing in the South Texas heat. After spending some time on Bob is the Oil Guy, I'm thinking of switching to Mobil 1 0W-40 for a little extra protection.

Is anyone using this in their 2nd gen V6?

 

I've run M1 0W-30 for quite awhile, but not 40. I would have a couple concerns. 1) VVT relies on oil pressure, not sure what affect going to a 40 weight would have. 2) Not clear to me if a 40 weight will flow enough, given the oil passages in the 1gr. Film should be better, but if the passages are too small, flow can be affected.

 

Can't speak to going from 30 to 40, but the 4-cyl 2TR-FE changed spec from 5w30 to 0w20 during its life, with no other changes. Same VVT as before, no issue. I don't believe that the viscosity will have any impact, since it isn't straight on whatever pressure comes off the oil pump (remember that engine speed affects oil pressure!). There are actually controllers that open and close the oil passages into the VVT units depending on how advanced they are and need to be. It isn't like balancing an incoming oil pressure against a spring. Its actually more like filling a hydraulic cylinder, except that its round instead of linear.

As for the oil flowing properly, once it is warmed up, the difference in viscosity will actually be very small. In fact, they could be exactly the same. The viscosity number actually describes a range of viscosities, and those oils of sequential values will actually converge at the middle. I.e., a "thicker" 30 will be the same as a "thinner" 40.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1824839

I would just stick with the 30. If you want the oil to be better, consider a 5w or 10w, which means that the oil will have less polymers to break down. Polymers added to oils are used to *increase* the viscosity as the temperature increases, but they break down with heat, causing the oil to thin out. Think of it like this; your 0w20, 0w30, 0w40 oil is actually an SAE0 or 10 or something light oil with a bunch of polymers added to it, so that at operating temperature, they will be equivalent to an SAE20, 30, or 40 at the same operating temperature. The bigger the spread, the more polymer there are added. If you want oil that stays at its design spec, you want less polymer additives, so a 10w30 oil will remain 30 under a lot more abuse than an equivalent 0w30, or even a 0w40.

There are a few mobile-1 oils that are available in 10w30 - "high mileage", or "extended performance".

 

I put this oil in and have run it about 1000 miles so far. The engine is certainly quieter. I thought it might be sort of a placebo effect but my wife noticed it, and she had no idea I had even changed the oil. She asked me if I "tuned it up or something". My fuel economy is about the same, but it is hard to accurately measure because I have been doing a lot of towing lately.
I'm going to have a used oil analysis done when I change it and I'll post the results.

 

I ran this oil for 11,866 miles. I meant to change it at 10,000 miles but just got real busy over the Thanksgiving holiday. This oil was used in some pretty severe, hot weather, towing conditions. I'm using an OEM oil filter and OEM air filter. The oil did great for me. Here's the used oil analysis. There was only a half of a quart makeup needed in this oil change interval.

 

Just realized the first image was too close and didn't show the universal averages. Here is another.