5w30 oil for the 2gr-fks?

Some swear by 5-40 Rotella (yes, diesel oil) because it is 100% synthetic and has a very high detergent composition to keep the engine clean. The first number is what "technically" affects your mileage but it would take sophisticated equipment to be able to tell the difference between 0wt and 5wt oil and choosing 0 vs 5 would depend on how cold it gets in your area...the second number is how much the oil resists breakdown at high temps, resists molecular shearing, etc. I'm thinking I will be switching to 5-30 Rotella for these reasons. Maybe even 5-40 during the summer when I'm towing a lot around the southwest states.

 

Eh yo - question: are you running your Taco in a place with high seasonal temperature variations? The 0W vs the 5W may make a difference if you are in northern Montana in the winter as the 0W will flow better at lower temperatures. If you're chilling in Virginia where if there is a winter mix in the forecast so they close schools and 20 deg F is what you define as "freezing balls" then you're probably good with the 5W.

To muddy the waters even more: according to Amsoil's website, synthetic flows better in the cold than conventional oil so if you are weighing 0W conventional vs 5W synthetic it may be a wash. Reference <- please ignore the headline. They get into the 0W viscosities half way down the page.

Edit: in my brief dig on the topic I read that engineers agree that most wear occurs at startup. Take that with a grain of salt as I have known a few engineers and rarely did they agree (but they were software engineers) but if that statement is accurate you want to get the right number on the W side for your cold starts. 0W will flow better in colder temperatures than 5W and synthetic will flow better in the cold than conventional. I cannot speak to the delta and if it is material - that I will leave for you to research.

 

some (not all) can't help themselves, they just have to change things for the sake of changing. There are some areas worth exploring, this one? I don't get.

 

That is because it will always "work fine" and most people are lazy and don't do research or even understand the factors involved...they just want to be spoon-fed. It is certainly not the "best" in terms of protection in every driving scenario, but it works fine and won't cause any problems down the road and that's good enough for most.

 

I agree. It’s their truck and since they haven’t or will never do a long life study. Hey you can carry 120v on a green wire. But it’s not normal and doesn’t follow NEC

 

Lol, I don't care what oil people run. 0W-20 is fine as is anything else up to 15W-40. The folks over at beloved Toyota who designed the engine have already said that is fine by putting it in the owner's manual for Mexico and in the FSM. The FSM lists GF-6A oils (which contains 0W-20, 5W-20, 5W-30, 10W-30), and 15W-40 as acceptable. Folks can stick to the OM if they want, but they can also deviate just fine. It simply doesn't matter.

 

I've got 5w30 synthetic in my 3.5 v6 right now, but won't be going back. It's fine for the summer temps, but the engine didn't like it when it was nearly -15 below in the winter. I think 5w20 would be a good choice.

 

You asked "how do you like Knoxville?" Not particularly well. My gas mileage has dropped to about 18 mpg. Navigating here is difficult. The roads are very hilly and curvy. There are no mountains for direction reference. Stop signs and lights everywhere. The roads are narrow (except the interstates). No shoulders in case of a flat tire. The folks here are great, tho. Moved here for the wife's benefit.

 

uh.... you are in the Smoky Mountains... you have some of the best sports car, motorcycle, roads in the country, within 30 miles of you. get out of the city, head to the mountains. north Georgia, the NC line and even northern SC are not that far, and run the spine of the same mountain group. get out and get you some. Ski

 

Ha, love it. I can recall running straight 30 weight to keep one from smoking too much!

Also had a Fiat spyder that I ran Rotella diesel oil in. I don’t even remember why.

 

I may be missing something -- this doesn't make sense to me. If you are concerned with cold start / cold temps you should be going down to 0W from 5W.... what you are changing in the quote above is the viscosity when you engine is warm (212 deg F). Think winter when you see the W... that is the side you should be changing if lower temperatures are a concern. Am I misinformed?

 

I've still got low mileage on my engine. I feel the viscosity of 5w30 in the cold winter months for start up needs to be lighter. My engine let out a loud groan upon startup on -15 degree morning, which it never did with 0w20. There's probably more than 1 reason why toyota recommended ds 0w20, other than fuel economy for the u.s. Other countries like Mexico are always warm, so 5w30 is fine. Same for the southern half of the u.s. Here in the northeast, I feel 5w30 isn't the best for year round.

 

I see what you are saying now - my apologies. You are currently running 5w30 and are considering going back to 0w30... your 5w20 comment was for OP, not what you are considering going to. My mistake.

 

Why not use viscosity recommend by manufacture?

 

The goals of toyota engineers are not always aligned with the goal of the end user. For a hypothetical, an engineer might choose a lighter oil that maximizes mileage and emissions at the expense of long term reliability. Or they might choose an oil that performs adequately across a wide range of temperatures instead of one that works optimally at a more narrow range in which the end user lives.

I mean, we often change our tires instead of sticking to those the engineers chose, right?

 

Tire choice varies a lot on our specific needs. An engine? It’s meant to propel us forward and backwards only, there is a difference there.

 

It’s not directly comparable, but it is analogous. Some people have different priorities than others, and certainly different priorities than engineers.

 

Here is some more evidence of lower viscosity recommended for the sake of fuel economy. Proven by a GM recall.

https://www.youtube.com/watch?v=pbEdr6Q6cKw

 

I run HPL Premium Plus 0w30. Good balance between minimum oil film thickness, cold start performance, and shear resistance. The only downside is cost, but it’s worth it for me.

 

• 0W-20 is optimized for fuel efficiency, cold-start protection, and engine longevity, especially under normal driving conditions.

• 5W-30 is thicker when cold and slightly thicker when hot, which could offer better protection in extremely hot climates or under heavy loads, but causes more wear on cold starts.