Which oil to use for a 2000 explorer with a 5.0 v8

[C420sailor]

Depends on your definition of “thinner”.

The problem is that this isn’t as simple as ‘lighter base stock equals better.’ There is actual engineering that goes behind oil weight recommendations from manufacturers.

Going from, say, a 10W30 to a 0W30 will result in a different viscosity gradient with respect to temperature. This will result in a reduction in viscosity across the board, except at whichever temp correlates to the 30wt. This is why we don’t have 0W100 oils and run them in every vehicle out there—the viscosity gradient would be steep as hell, and the oil would be more resistant to flow than desired at nearly every temperature.

Now, none of this is necessarily bad. But, you have to also remember that the characteristics of an oil system are a major factor. An oil pump, like most things in the world, has a sweet spot. There is a particular fluid viscosity that will make it operate most efficiently. In fact, in some types of pumps that are designed for “thicker” fluids, an excessively thin fluid won’t pump well—or at all.

In other words, thinner is not always better, and it does not always result in the least startup wear. Especially in an older engine, an oil with lower viscosity may not develop pressure as rapidly due to larger bearing clearances and such. A higher pump RPM may be required to overcome those losses and develop sufficient pressure. Pressure is of critical importance.

The only surefire way to determine which oil weight is best is to instrument the engine and analyze the data. I doubt anyone here is willing to do that, so the best method (in my opinion) is to stick with the manufacturer’s rec unless you have a good reason to deviate (like extreme climate or wear) and do so carefully and incrementally.

 

[CDW6212R]

... so the best method (in my opinion) is to stick with the manufacturer’s rec unless you have a good reason to deviate (like extreme climate or wear) and do so carefully and incrementally.

Well said. I choose the recommended oil viscosity if possible, and alter that if needed, based on the engine's condition, or the weather I drive in. I would love to be able to monitor oil pressure and temperatures, in actual driving conditions. That would help a bunch to know if the oil being used is adequate or ideal. Where I live I'd like to see lower oil temps than what I suspect they are, and use a slightly thicker oil to gain pressure. But I don't jump to a conclusion that the choice should always be thicker etc.

Using top quality oil and changing it regularly is the most important. Cheap oil and extended(forgotten about) intervals, those create worn out engines fast.

I go back to my stock 99 SOHC 4.0 engine just before the trans went. I had changed to Amsoil Signature series synthetic in the May range. At 9000 miles after checking it often(it didn't use oil), the oil was not black, it was still transparent. I had also been using an aftermarket air cleaner(Volant), and an Amsoil filter inside that. So very clean air and excellent oil for an engine that wasn't hurt before I bought it, the oil stayed clean. Unfortunately I hadn't tightened the air filter clamp enough, and I found the oil black about a week after the last time I had looked at it. I removed the top of the air cleaner off, and there was the air filter laying in the bottom. I put the filter back on more tightly, and changed the oil right after that.

So it is possible to have an engine that doesn't use oil or get it very dirty, but things have to be taken care of very well to do that. It's hard to pay big money for oils etc, for a used engine that someone before had not taken good care of. We do the best we can.

 

[C420sailor]

Yeah, I’d love to see some oil analysis. I do it on my airplane (it’s fairly industry standard) and it is worth its weight in gold, especially for monitoring wear.

I’m too cheap to do it on my vehicles though haha