So I had my uncle asked a few engineers at ford about this because my parents car 02 mountaineer has a 4.6L and ive been using 5w20 mobil 1. I think there answers are complete garbage. Here's what they said.
I am going to assume the customer has a 4.6L engine since he states using 5W-20 oil. It is best for the customer that he stays with 5W-20 oil to make sure he gets the best protection (and fuel economy) for his engine. 5W-30 should only be used with 4.0L engines in the Mountaineer. Below is what we state in owner guide:
"Use Motorcraft SAE 5W-20 or an equivalent 5W-20 oil meeting Ford specification WSS-M2C930-A. SAE 5W-20 oil provides optimum fuel economy & durability performance meeting all requirements for your vehicle's engine".
Per your inquiry here is the answer. In layman's terms your brother should stick with the 5W-20 weight oil since that's what specified and what the engine was tested with. The 5W-30 is going to have a higher viscosity when the engine is cold and therefore may not provide ample lubrication during critical start time.
That may result in accelerated wear or eventually possible engine failure in the worse case. Both oils have the same viscosity when warm but from what I recall the 4.6 modular is a rather tight engine that requires the 20 weight in cold engine start up in lower ambient. Bottom line is use what we recommend.
I am going to assume the customer has a 4.6L engine since he states using 5W-20 oil. It is best for the customer that he stays with 5W-20 oil to make sure he gets the best protection (and fuel economy) for his engine. 5W-30 should only be used with 4.0L engines in the Mountaineer. Below is what we state in owner guide:
"Use Motorcraft SAE 5W-20 or an equivalent 5W-20 oil meeting Ford specification WSS-M2C930-A. SAE 5W-20 oil provides optimum fuel economy & durability performance meeting all requirements for your vehicle's engine".
Per your inquiry here is the answer. In layman's terms your brother should stick with the 5W-20 weight oil since that's what specified and what the engine was tested with. The 5W-30 is going to have a higher viscosity when the engine is cold and therefore may not provide ample lubrication during critical start time.
That may result in accelerated wear or eventually possible engine failure in the worse case. Both oils have the same viscosity when warm but from what I recall the 4.6 modular is a rather tight engine that requires the 20 weight in cold engine start up in lower ambient. Bottom line is use what we recommend.
one thing I've learned about engineers, listen to every other word they say, read from right to left and then form your own opinion. I deal wth wth Ford engineers just about every day
) Back then everone used 50w in there big blocks. We knew a "trick"; use the thinnest oil that you can maintain pressure at. For most it won't matter which you use but things change and lighter is the way to go. You know we used to make HP running 160 thermostats or no thermostat but it is the opposite with new engine technology. Being able to evolve is the key to survival. Don't get stuck.
