DPE

Might be the wrong section, but most of the road course guys seem to hang out here and that's where this applies. My car is a 2010 GT that I purchased new in February. It is 100% stock as far as the engine goes, and I suspect it'll stay that way or at least close to it. Much money goes into suspension and brakes . I chose to stick with Motorcraft 5W-20 synthetic blend because it's cheap, it's at least kinda synthetic, and it obviously meets all warranty requirements. Also, per bobistheoilguy.com the recurring theme seems to be run as thin an oil as your car can because it gets up to temp and thins out quicker at startup which is where most engine wear occurs. I changed it at 1000 miles, and then at 4000 and 7000 (and will go every 3000; I know, way too often, but the car is run very hard at times so it can't hurt).

In looking at the Boss owner's manual the other day (just for fun; not getting one), I noticed they recommend running something like 10W-60 for cars that are on track all the time. That made me stop and think at least a little bit about how thin 5W-20 is, and if I'm doing damage to my motor running that thin oil on track. Doubt it, just made me think.

Now, my car is not on track 'all the time', but in a normal year I expect to get to 8-12 events. And I do some road trips to twisties where the motor is wound up pretty high for extended periods of time. I typically run in the fastest run group at a given event, so the car is being subjected to something fairly close to actual race conditions. It's not being subjected to proper race driving mind you, but I at least try to turn good laps .

I guess the question is, has anyone with a 4.6L ever had an oil-related engine failure just from plain old 'severe' use? And if so, were they running 5W-20? Is there any data to suggest that in extreme situations 5W-20 synthetic blend will break down in such a way as to provide inadequate protection? What does Roush recommend for their cars, which are more highly stressed due to the blowers and are at least a bit likely to see severe conditions?

I suspect with the 4.6L being a relatively unstressed motor in stock form (compared to, say, a 444hp 5.0 that revs another 1000rpm higher), combined with the fact that my car has the oil changed frequently and doesn't get constant track time, I don't have much to worry about. Certainly not going to throw 10W-60 in there. But I'd like to hear what folks have to say on this ever-debatable subject. . .

JAJ

You're good with the MC 5w-20 oil. I had an oil analysis done on my 2011 GT 5.0 factory fill, which is 5w-20, and it was fine after 5,000 miles (oil service indicator came on at that mileage) including about 1,500 track miles over 10 or 11 events.

As you found from reading BITOG, thinner oil flows faster and that removes heat better than thicker oil. If the engine passes Ford's extensive and challenging endurance testing with the 5w-20 (and it wouldn't be recommended if it didn't pass) you can use it with confidence. Despite the extensive and passionate debate that always ensues after a question like yours, very few engine oil-related failures actually happen unless the car is seriously under-filled or the oil isn't changed at the required intervals.

Sleeper_08

I had a Roushcharger dealer installed on my 08 GT and run Mobil 1 5W 20. The car now has over 30 track days on it and "touch wood" the engine seems fine.

I change the oil and filter after after every 3 track days and use Motorcraft oil filters.

drew2000

Nothing wrong w/ 5W20 oils. I use them in daily drivers and the thinner oil really helps in vehicles that have frequent short trips with cold starts. In these "normal" applications, 5W20is fine.

5W20 oil was developed to eek a 1-2% CAFE MPG improvment (very important to the auto makers) over 5W30 and 10W30 oils. The Boss uses 5W50 oil, and the new Ford EcoBoost V6's are all spec'ed for 5W30. Why? In those more severe applications, 5W20 may not offer adequate protection.

FWIW. I run 5W30 synthetic in my '11 5.0 and the engine loves the stuff. Very quiet valve train and smooth operation. 5W30 is bit heavier than the 5W20 and works great for me on the street.

IMHO, I would run a full synthetic 5W30 or 0W40 for a car that's run hard and not a short-trip grocery getter. If you want to stick with 5W20, at least run a full synthetic like Mobil 1EP, Pennzoil Ultra, Amsoil etc. For any of the mentioned grades, a 5000mi OCI would work well as would a Motorcraft oil filter.

Ansibe

DPE, your car and mine are very similar, except mine has the 5.0. I do about the same number of track days as you. I use a full synthetic 5w20.

Oil pressure is built up in a journal bearing based on the bearing clearance, shaft speed, and oil viscosity. At the track your shaft speed is very high (high engine rpm) leading to high oil pressures inside the bearing. I believe that these high pressures and shaft speeds can break down the oil's polymers quickly, so I won't run a heavier oil. There is a good argument for the oil thinning out at high temperatures, but synthetic oils are thermally quite stable so I accept this risk. Because of this, I agree with Drew2000 that a full synthetic is a good idea, and I actually think that a slightly higher viscosity (5w30) is probably beneficial in the low rpm street engine.

The Boss engine is a special beast, made for the track and designed for 5w50. It probably has larger journal clearances, and therefore is a little less tolerant of short trips/cold starts.

I think Ford engineering has it right.

DPE

Good stuff. Thanks for the input guys. Going to stick with 5W-20 for sure, but may consider Mobil 1 5W-20 instead just to be on the safe side; however unncessary that might be. Sounds like JAJ had proper analysis done and after 1500 track miles (good on you, sir, getting to the track that much! And remind me not to buy your car used ) was fine with the Motorcraft stuff, so that's a pretty good clue that all is well with Motorcraft. Anyway, happy to get some affirmation that I'm likely not doing any damage to my motor running what I do. And I didn't ask, but can't imagine why one would run any filter other than the Motorcraft FL-820-S? Cheap and good quality as far as I can tell.

Import_Slaya

Several years ago I had a Blackstone analysis done on mine after a few hundred street miles and a weekend at the track and it indicated that it had sheared down to just slightly lighter than a 20 weight (off the low end of the range given). After doing some research on this and participating in a thread on cornercarvers.com where one of the engineers who designed the 4.6L 3V (and is also an avid racer) suggested a 30 or 40 weight, I've been running 5w40 or 10w40 Mobil 1 ever since.

I'll see if I can dig up my report and the link to cc.com.

Import_Slaya

I've attached my oil report and here's the link--interesting reading: http://www.corner-carvers.com/forums...highlight=5w20

At this point, I thought it was fairly common knowledge that most of us tracking the car used a 30 or 40 weight, especially if you are running in hotter climates.

DPE

Judging by this thread, this does not appear to be common knowledge .

Interesting read. The Scott guy certainly has the qualifications it looks like. Yet experience in this thread and actually in that thread further down indicates 5W-20 to be fine, does it not? I'm not trying to make an argument, especially 'against' Scott, who clearly is the resident athority on the subject, but the thing I haven't yet seen is a failure attributed to 5W-20 (not to say it hasn't happened, or perhaps my reading compreshension is bad, but I haven't seen it). The thing I have seen is a number of people running 5W-20 that don't have any issues, including guys that have run it for quite awhile in older Mustangs.

Your oil analysis is interesting I_S. Others claim to have had it done after MUCH more time in the motor and it comes out 'fine'. Not sure what to make of that. Also don't really know what those numbers mean; what kind of problems does a viscosity on that end of the range mean? As long as the engine can maintain oil pressure, you want as low a viscosity as you can get, right? What does an oil analysis on brand new MC 5W-20 look like?

Anyway, more to think about I guess. Dammit. Didn't want to have to think about it! Maybe I'll just be the test case and run 5W-20 until the motor dies and see how far I get .

Ansibe

Two more cents...

It's important to separate pump oil pressure and bearing journal pressure. The pump pressure is created by your oil pump (duh), and serves to move oil around the engine. This function is critical to bearing life because without oil they over heat and melt. Your oil pump can manage almost any commonly available viscosity of oil. Very high viscosities could cause cavitation in the pump, and that could seriously affect oil availability.

Journal pressures are very high, and prevent bearing failures. Journal pressure is created by a shaft rotating in a plain bearing in the presence of oil. The shaft actually rides on a wedge of oil, preventing metal to metal contact. Oil viscosity has a huge effect on the "wedge"; too low and the wedge collapses, too high and flow is compromised.

The 5.0 engine is designed to operate with 5w-20 oil at normal temperatures to the engine rpm limit. My track use is within those limits, so I use 5w-20. I warm my engine up carefully so the oil viscosity is stable, and I use a full synthetic to deal with the high oil temperatures seen at the track.

My engine is 100% stock.