If anyone using 5W-30 every gets denied warranty coverage based on the fact they used 5W-30 just let me know and I will fax you the two work orders I have where they both state that the dealer (Ford approved) used 5W-30 on a 2001 where the manual “recommends” 5W-20. You will have no problem with that in hand. Nothing your dealer can do since 5W-30 is an approved oil to use regardless that the manual states 5W-20.

gopher:

You have an interesting post and one which concerns me, or at least makes my point on why it’s better to use a 5W-30 rather then a 5W-20. You say that the 5W-30 “may” shear down to a 5W-20 after 3,000 miles. No problem there, the problem I see is that you also say a 5W-20 can shear as well, maybe not as much. The point being if the 5W-20 shears “at all” that is very bad news for the motor. It would mean the oil is even thinner then a 20 weight and less protection for the motor under normal conditions and especially under any kind of a load.

We all know you can only go so thin in weight before you start causing major problems to the motor. The reason that is true is because if thin was better then it would be best to just run 6 qts of WD-40 in the motor, now that’s thin…

 

Someone mentioned something about using I believe a fuel treatment now and then. I use a fuel injector cleaner in my fuel at every oil change of 3,000 miles. The dealer thinks that is a great idea and told me to not to even bother doing the maintenance (they recommend) on cleaning the injectors at I think 30,000 miles…

 

Yes, 5w20 oils will shear some under use. Yes, nearly all 5w30 dino oils shear under use. Your point is that 5w30 provides a better margin for error should the oil thin out too much. My point is that is faulty logic.

I've seen 5w30 dino oils shear to mid-range 5w20 oils is less than 3000 miles. I've also seen them hold up over 5000 miles. Lots of variables at play here.

With the 5w20's the worst I have seen so far is a 7500 mile run in a four cylinder that pulls 4,000 rpms cruising at 80 mph. It had sheared from 8.5 cst to 7.5 cst, still solidly within 5w20 land (Allowable Range is 4 cst-9.3 cst for 20 weight). I've seen 5w30 shear from 11 cst to 7.9 cst in 2500 miles in one of my vehicles, with no fuel dilution or other mechanical faults, and yes, it was a major brand.

So which offers better protection: The 5w30 oil that slipped 3.1 cst in 2500 miles? Or the 5w20 that slipped 1 cst in 7500 miles, which is the worst I've seen yet? I've seen too many 5w30s that end up being MUCH thinner than when they started. I would argue that the oil that most closely maintains its specs to what it was when it came out of the bottle is the one that is holding up better over time.

There is one significant difference between the two oils, and it is this: Ford, in particular, has MUCH tougher standards for a 5w20 oil to meet its specs compared to what tests a 5w30 oil had to pass to meet previous Ford and other industry specs. The end result is that the 5w20 oils on the market today are MUCH more shear stable than their 5w30 counterparts, bcause they have to be to carry the spec.

 

your all forgeting one thing. The reason why ford developed the 5W20 viscocity and tested it so thoroughly is becaue they needed better CAFE numbers.

New viscocities= less consumer confidence=corperations and oil companies providing "sound scientific data." I especially like the Ford company line "the clearances in the engines are too tight to use a 5W30 weight oil." This is total and complete BS!

 

I have said the same thing in the past and continue to believe the statement that Fords main reason for using 5W-20 was CAFE. I did read one time somewhere, don't know if it was Ford or somewhere else the comment about the clearances in the engine are too tight for 5W-30, yet none of the clearences have changed from my knowledge 97-03. The new models I don't know the 04's.

As far as my knowledge knowing the clearances have not changed is both service managers at both Ford dealerships I go to have told me that and that is why they continued to use the 5W-30

 

When doing work, I am able to hang out in the shop (Ford) with the mechanics. Everytime they see me the probably think ahhh Xhit! here he comes again, and that is because I ask so many damn questions.

None of the mechanics said anything about viscocity being the cause of premature engine wear or oil deprivation. I have not heard of one case.