I have a 2007 toyota tundra 5.7 liter sr5 with 250,000 miles on it. My mechanic says I should run 5w 30 full synthetic in it. I trust what you have to say about this. What should i use if not 5w30. I also use Kendall GT max oil. Is there a better oil for my tundra?
What does the owner's manual say? Stick to whatever the owner's manual says and nothing else. Cars aren't designed in the 70s anymore, where you had to choose based on operating conditions. Cars could run on almost any, heavier oil. If you choose the wrong oil, the engine will wear out faster.
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What does the owner's manual say
Straight from the owners manual, page 545:
5.7 L V8 (3UR-FE) engine
"SAE 5W-20 or 0W-20 engine oil may be used. However, SAE 0W-20 is the best choice for good fuel economy, and good starting in cold weather."
"Mechanic" is only a title, then.
Unfortunately yes... It's possible 5W-30 was recommended for smaller 2007 Tundra engines and he was thinking of them. A "good mechanic" should also know how to say, "I'm not sure" or "I don't know".
What should i use if not 5w30.
Toyota recommends 0W-20 or 5W20 full synthetic. Their reasoning is "for better fuel millage". An additional reason is because the lower viscosity lubricates better on engine start up, where most engine wear actually occurs.