Has anyone tried this? If so, what were the results?

 

is that engine spec'd for 5w20??????????????????????????

 

I would have no concerns with running 5w20 in your engine, provided you run Redline oil, which 5w20 has the HTHS viscosity of a 30 weight.

In fact I have just that in a '92 Aerostar that is NOT back speced by Ford for 5w20 ('93 is).

Oh, and I have Coastal 5w20 in my '95 4.9L F150 that specs 10w30 (Ford back specs 5w20) and I normally run 10w40 for better oil pressure. Now being winter and my shorter trips (usually not over 15-20 miles) the 5w20 really does not get much thinner than my 10w40 does in the summer, that is the 5w20 has not yet gone below 39 psi at 2000 rpm, where the 10w40 will get to 40-42 in summer. But I am only running this as a rinse. It did teach me that I do not need 10w40 in winter, so I will be filling next week with 10w30 for the winter months.

 

A nine year old motor will most likely have over 100,000 miles on the clock. I wouldn't recommend a 5w-20 oil for that engine if it has been using a Xw-30 for all of these years. As the engine wears/breaks in, at the rod bearings, the rods do not follow a perfect circle around the crank. It is a slight eliptical path that it follows. This is so that the oil can form a wedge just in front of the crank and the crank "rides" this wedge of oil as it goes around. Should you use a thinner oil, this area may have enough wear at 100,000 miles so that the oil doesn't form a wedge but literally runs out because the clearance is too much. Accelerated wear could be the result. If the engine is fresh/rebuilt, I wouldn't hesitate to run it. On an engine with high miles-no.

 

you can also see the tests on the 5w20 run in 40 year old FE's. check out the FE forum.

 

So Flash, would that be the case even with the Redline that has the high HTHS? If so, maybe I should not be running it in the Aerostar. Also, are you saying that no high mileage engine should run 5w20?

 

TP, fresh motor or where the exact clearances at the rod and main bearings are a known and it is still a tight engine, you can run the 5w-20. If the engine has high mileage that has been run with higher viscosity oil, no. The HT/HS rating will be a non-factor as the oil won't stay on the job as it should. Only way to keep it on the job is to run the same viscosity oil that it used in accumulating the miles or a higher viscosity oil. This is the main premise behind the high mileage oils. Most all of them are on the upper end of their viscosity range which in turn promotes a slight increase in the film viscosity at the bearings and that in turn promotes slightly better oil pressure throughout the lube system.

 

Thanks Flash, this Aerostar has always had 10w30 for 120,000 miles. If the 9.1 cSt (100C) Redline is going to screw up the engine, then I could drain off 1.5 qts and pour in that much Redline 10w40, which I have, and bring it up to 10.6 cSt. Probably a good idea since I was planning on running this stuff about 7 or 8 thousand miles and am only 1700 miles into it?

Of course, if the oil instead of forming a wedge, runs out the bearing, would that not show up as significantly lower oil pressure? And it also would tend to starve the top end. So if an old vehicle holds decent oil pressure on 5w20 it may be OK?

 

TP, most of the oil pressure sensor locations on Ford or GM engines are at the oil filter. It will look great at the filter but actually have little to no flow at the bottom end and not show up on the gauge. If it is cold where you are at ( it was 92F here today and still over 80F as I type this) and appears like it will stay cold, you might want to drain off 1 qt and put the 10w-40 in. Otherwise, 2 qts would be more ideal. But be careful, we might have to refer to you as the Redline Amsoil Blender .

 

I appreciate the information from each of you. The truck only has 88,000 miles and consumes no oil at this time. I have decided to stay with 10w30 Motorcraft,Kendall,or Trop Artic Synthetic Blend and Wix Filter every six months or 5000 miles. Why fix something that is not broken?

 

Well Flash, it looks like I may be okay for the winter because this van gets mainly short trips and the oil should never get warm enough to be a compromise in the bearings. Next summer, though, is another story. Well I have the 40 weight and can apply it generously at that time. Thanks. From now on, no more 5w20 for me unless under the criteria you set out above.

 

Flash,

You said: "...Should you use a thinner oil (5w20), this area may have enough wear at 100,000 miles so that the oil doesn't form a wedge but literally runs out because the clearance is too much. Accelerated wear could be the result."

Would this amount of potential "accelerated wear" be enough to show up on a UOA, in your opinion? If consecutive analyses were done with 5w30, then 5w20, & the UOA results were roughly the same, couldn't one reasonably conclude that the 5w20 would be fine to use?

 

wavinwayne, probably not in a spectroscopy type test. This is the typical test that you send in your sample and for $20.00 they tell you the wear metals and TBN. In this type of test, the sample is gassed and the gasses exposed to light and the colors that are in the gasses are read as to the amount and type of color/metal. With accelerated wear where oil starvation can be a problem, the particulate matter will be too large to gas. A UOA may turn up that everything is great but a ferrography test with a particle count may show major wear metals. Most folks aren't going to spend the $100.00+ to have the test run unless they suspect something and generally, the average Joe isn't going to spend the bucks even though he may suspect a problem. Sometimes, ignorance is bliss.