Manual states 5W-20 only and that's what I use.

GaryG

 

Outside temp currently 15° and close to zero for lows next week without the pleasure of a heated garage.... you do the math.

Gary's much closer to the equator.

 

When I was a kid on the farm, we always ran SAE 30 in the summer but then in the fall changed over to SAE 20 for just the reason you are referring to. Do you stay with 0W-20 year round?

How many miles do you have on your FEH? Have you been using the 0W-20 all along? I'm considering using it too. On the Mobil 1 site it says this about 0W-20:

"Mobil 1 0W-20 Advanced Fuel Economy is engineered to deliver outstanding engine protection and to offer improved fuel economy benefits in vehicles where SAE 0W-20 or 5W-20 motor oil is recommended. This low friction, fully synthetic formula increases engine efficiency and offers the best fuel economy in the Mobil 1 line. "

 

This is my 2nd oil change with 0w20 so not long, but plan to stay with it. Odo reads about 32k. Warmest temp this summer was probably about 95°F (and not high humidity either) so only used AC on long trips about 10 times. I do too much Interstate driving to know if it made a difference mileage-wise.

I find it hard to find the 0w20 locally. I checked about 5 stores before I found one that handled it and they had to go in the back room.

 

If the FEH manual said to use a thinner 0W oil in colder weather I would but it doesn't. My concern is warranty and what works for me. Start-up is the big concern so that is why I use approved synthetic oil. Ford set the operating temperature of our engines so I stick to their requirements on oil specs. If you want to read more about oil, here is a good link:
http://www.bobistheoilguy.com/cms/

GaryG

 

Years ago the vehicles we drove didn't have the requirements they have today. In order to meet the emissions requirements and fuel economy mandates, engines are designed to operate at 212 degrees (f) year round. The oil passages, filters and cooling systems are designed for a specific viscosity (cSt value) at operating temperatures - and for us that is around 9 cSt.

Many people used to think that oil pressure = lubrication. NOT TRUE.
Flow - lubrication.

Most engine wear occurs at start-up. Starting with an oil that has a cSt of 9 at operating temps, we can say that oil thickens as it cools. The thicker it is at freezing or less, the more wear and less flow. If your vehicle usually incurs freezing start-up temperatures, you would probably bendfit from a full synthetic 5W20 or 0W20 oil (as they are "thinner" at these temperatures.)

BUT - they are considrably more expensive than a synthetic blend oil. And if you are going to follow the manufactures maintenance schedules, and you don't usually ibcur below freezing start-ups, the bendfits of a full synthetic are negligible. Most manufacturers design around a synthetic blend oil due to the cost of ownership issues.

Use a full synthetic is you wish, but realize there is little if any benefit in doing so.

 

[these temperatures.)

BUT - they are considrably more expensive than a synthetic blend oil. And if you are going to follow the manufactures maintenance schedules, and you don't usually ibcur below freezing start-ups, the bendfits of a full synthetic are negligible. Most manufacturers design around a synthetic blend oil due to the cost of ownership issues.

Use a full synthetic is you wish, but realize there is little if any benefit in doing so.[/quote]

You are mistaken. There is tremendous advantage to using 100%
synthetic in warm areas or cold. The temperature inside your motor can reach 700 degrees and at that temperature conventional oils do not lubricate very well and break down forming sludge. The biggest reason for using synthetic oil is that it can stand those high temperatures without breaking down or forming sludge. The original mobil one was only a 5 weight oil but even then it was far superior to all conventional oils manufacturered at that time and in 1976 i reluctantly started using it in a motorcycle with never any problems. I have used it ever since in all gassers.

 

0W-20 also.

Keep in mind what those numbers mean. The key is the 20 as that's the hot number. The w number indicates the viscosity when cold and it is thicker when cold than the hot viscosity number, its just thinner than a straight 20 weight oil would be when cold.

 

I disagree with the comment that there is little benefit to using a 100% synthetic. I believe that a blend is mostly dino oil and thus the characteristic of the oil inside the engine will be dominated by that large fraction of dino oil. However that benefit won't show much if you don't keep a car beyond 100,000 miles.

Benefits:
1. Far less internal wear.
2. Far higher thermal stability, therefore next to no sludge production.
3. Even with the same weight of oil the pour point is lower in cold weather.
4. Finally, a small but measurable increase in fuel mileage.

In my case a 92 Suburban, OEM engine, with 423,000 miles on it still gets around 5,000/qt. I put it on Mobil One at 5,000 miles.

 

Although I rarely keep a vehicle after it's paid off, those are the 4 reasons I use synthetic oil.