5w20 in a 4.0 v6, should I dump it?

I'm well aware of why you wouldn't use a thinner oil. I was just curious what you thought. Many people post statements without knowing the reason for them. For example. 5w30 is better than 5w20 just because it isn't 5w30. For the colder states, it's actually better to use a thinner oil to help the truck run smoother and warm up to temp easier.

 

Toyota specifically said "no" to using 5w20 in the 1GR-FE. I asked back when the TSB came out saying it could be used in the 2.7.

 

For cold weather starting, go with an oil that has a lower cold viscosity (the "X" in XwY, such as 5w30 or 0w30).

Once the engine is up to operating temperature, outside temp has virtually no effect on the lubrication system. So you want the hot viscosity (the "Y" in XwY) to be the same or nearly the same.

 

I think you're referring to 0W20...the 5W20 is approved for the GR series engines.

The TSB covering this is EG018-06, I just re-read it. Make sure the oil has the API starburst and try to find an SN oil. They should be pushing the SM oils off the shelves soon! My preference is to use a good quality synthetic and that is all I usually find at my Walmart in 5w20 anyway...Penzoil Platinum and Ultra, Castrol Edge or Mobil1.

Yes, it's more expensive. But I offset that by using 10,000 mile oil change interval.