Originally Posted By: aquariuscsm
I wonder if 5W50 would give the GT a little bit of "buffer" room to keep the engine protected? In my observation,5W50's seem really thin. They feel thinner between the fingers and pour thinner than 10W30 (VERY scientific,I know haha). Shake a bottle of 5W50 and 20W50 side by side at room temperature and there is a huge difference.
In my experience a typical 5w-50 shears as you pour it out of the bottle. For example if one is auto X and only run the oil for a single event then the oil should retain its viscosity for long enough such as a typical race weekend then change the oil.
But a long drain on a 5w-50 would concern me however considering there is very little difference mechanically between the Ford 5.0 that requires 5w-50 and the version that calls for a 20 grade its entirely possible that Ford expects the oil to shear and they don't care because the engine can survive on a 20 grade so even if the oil shears down to a 30 from a 50 it's no biggie because it's OK with a 20 grade,so longer drains don't concern them.
Speculation of course.
Originally Posted By: wtd
Originally Posted By: hatt
Agreed. No idea why someone would want to run the absolute minimum spec oil in an expensive performance vehicle.
Maybe because some of us want to keep our warranty intact and for my car, there is no other recommendation other than 5W-20. My experience with Ford's warranty is don't give them any reason to deny you warranty because they will if they can.
Wayne
Wayne. Any idea what ford specifies for the mustang in Europe.
If it's a 30 or 40 grade then they cannot deny warranty coverage if you use those grades. They can't say it's ok to use when you like over there,but if you use it here we are going to can your warranty. They can't have it both ways.
Regardless they have to prove the lubricant caused the specific failure. Which if using a typical euro spec oil just isn't going to happen,especially at the shorter intervals we here typically run in comparison.
If you drive easy then a 20 grade is more than adequate and if it's got an oil cooler I'd also have much more confidence in running a thinner grade.
The key is oil temps. If the oil temps can stay under 240f even at full pedal then a 20 grade easily works however once you start getting real hot the oils film becomes much thinner,and a 30/40 grade will have just that little bit more film thickness which could make the difference in certain situations.
No engine ever failed using a thicker oil than specified(within reason)and anyone with any sense knows engines aren't designed for a specific grade of oil. If that were true the oil would have to be pre-heated to operating temp and strict controls put in place to make sure the oil never wavers from that specific temp/thickness.
Engines are built to use a range of lubricant grades. Depending on temps both inside the engine and ambient one makes a choice.
Sure a 20 grade is adequate for most every situation in typical street driving however when you are beating on it it only stands to reason thicker is better if the oil temps exceed whatever temps the 20 grades oil film thickness becomes compromised.
And considering the certifications a typical euro spec oil meets and the exotics that call for them I'd feel much better knowing the oil in my performance car is stout enough for a Bugatti,and isn't the same oil that a civic calls for.
Ultimately it's your choice of course. And if you granny drive you'll never need the extra headroom a 0w-40 allows for however if you drive that car like it's meant to be driven daily you'll quickly learn that one size fits all usually doesn't.