What's heaviest oil I can use 05 expedition

[USMCBuckWild]

We have a 2001 Expedition since new, ran recommended oil weight till 150,000 miles, adding a can of Engine Restore every 3500 miles. As miles went up , increased oil weight to 10w 40, then when we hit 300,000 miles, I run 20w 50 Castrol in it, still runs great. It now has 360,000 on it, used a Qt between changes. I have always used Castrol, and Fram filters along with Engine Restore. As the engine accumulates miles, the clearances increase, therefore my theory says increase oil weight. We also have a 2012 King Ranch, I am using the same theory with it. It has a little over 100,000 on it, still running 5w 20 Castrol syn blend, but am using Engine Restore. I use these products in every vehicle {6] that I own, boat, has a ford 351W in it, and mowers and such. I have had no bearing failures in 30 years.

While your logic has some merit and truth, i have to disagree with you in regards to the Ford modular v8.

While you are correct in the fact that the bearings/rotating assembly wear down with higher mileage, the oil passages and oiling system (which is designed for a narrow range of oil viscosities) does not change. Too thick of oil and the oil pump can't push it, can't get it through the oil passages, oil filter (which is also metered for certain pressures) to the components that require a SPECIFIC oil pressure to work properly. Timing chain tensioners, cam phasers, cam followers, all require a SPECIFIC pressure.

Not trying to insult your intelligence, but think of it like this:

If you grab 1 straw and 2 glasses, fill one glass with water and one with maple syrup; can you suck the the maple syrup out as quickly and consistently as the water? (Yes I understand the difference between hydraulic suction and hydraulic pressure, this is just a layman example) This is a crude example of the difference in the viscosities of the oils and what the lubrication system is attempting to do.

Yes, in older engines with solid lifters and mechanical timing chain, a thicker oil at high mileage does aid in retaining appropriate pressure in a system designed with oil pressures that are partially metered by the bearing tolerances. But, even then at some point too heavy a viscosity is just too thick. The old used car salesman trick of adding a quart of gear oil to a upper end knocking engine to quiet it down is no longer going to work.

You may not have had a bearing failure in 30 years, but have you had any other failures?

 

[JExpedition07]

Idk I wouldn't put anything with 40w in the name oils wise in my truck. The whole reason I bought this truck was because when I opened the hood and turned it over for the first time it sounded sooooo smooth. I just do Motorcraft Synthetic Blend 5W-20 oil with a new Motorcraft FL-820S filter every 3,000 to 4,000 miles and the engine seems to be good and smooth at that interval.

 

[jeff kushner]

Man, if I just had a nickle for every oil thread I've seen.......like many of us, I would be financially wealthy!

A lot of the myths surrounding oils and viscosities were initiated by the oil companies themselves back in the 60's and many live on today.

Fact: Honda began the wholesale use of insert bearings, opting to rely on high oil pressures instead of the time-honored tradition of bathing the bearing(be it ball, needle or roller type) in oil.

In those engines, at cold startup.....using a straight high viscosity oil CAN & WILL cause damage to insert bearings but not necessarily will damage other types of bearings because they tend to hold oil from the previous run cycle.

Our friend above with the 360K engine is no doubt telling the truth....and he's right, Castrol makes a very good line of motor oils. I used the exact 20/50 in a '72 CB350 Honda engine for over 35,000 miles of year-round riding without and bearing issues....the thing that saved that engine as well as the Expy engine was the 20W component of the 20/50 for the same reason that USMC outlined a little differently.....

We...or I should say....most of us know the deal....keep it filled with a good quality, clean oil and you'll be doing the best you can as an owner as your part of taking care of your engine. The type matters not quite as much.....

jeff