5W20 Motor Oil??

[ajsam01]

I noticed that my owners manual doesn't list any other weight motor oils as alternatives. That seemed odd to me. I know that Ford "recommends" 5W20 because it allows them to claim better gas mileage ratings. I'm not so sure I agree that oil so light can provide adequate engine protection. I grew up on 10W40 and relucantly changed to 10W30 in the 90s. Am I too old school? I'd really like to run at least 5W30 but not if it means voiding my warranty.

[indy85_starion]

Is the owner's manual referring to conventional or synthetic oil?

In the regular conventional oil world, believe it or not 10W30 is better than 10W40.

10W30 is something like 40 percent straight 10 weight oil with the remaining 75 percent being additives to make the oil act like straight 30 weight at operating temp.

10W40 is something like 15 percent straight 10 weight oil with the remaining 90 percent being additive to make the oil act like straight 40 weight at operating temps.

Therefore, 10W30 is composed of more lubricating oil than 10W40. Of course, I have oversimplified this in my explanation, but my point is still holds true.

My current car is turbo-charged, so heat is a major concern. I have put over 200K miles on my engine using Castrol GTX and Valvoline...
straight 30 weight year-round except when climate falls below freezing -- then I run with 10W30.

I am contemplating purchasing a recent model T-bird. Unless I was using a synthetic like Mobile One, I would never use 5W20. If tolerances are really that tight, I would run straight 20 weight. Well maybe, 5W20 below freezing.

5W20??? I would approximate that to be 40 percent straight 5 weight oil with additives to act like straight 20 weight at operating temp. Seems much too thin to me!!!!

[bigbrownbird]

Hello,
i'm down from the 77-79 forum, but i have been working my way through college with oil changes, for the first 2 years doing them, and the last year just selling them. The reason ford went with 5w20 is because the clearances are tighter on these newer engines. My friend who is a service manager at a ford dealership informed me of that tidbit of info. If you use a heavier weight, such as 5w30 or heavier, ont only will it void the warranty, you take a risk of cooking your new engine! I agree, 10w30 is what i run in my old vheicles, but if I did have a newer ford, I'd make sure to fun the required 5w20. Most major oil brands have it on the market now.
I hope I helped you out.

Lee

[shrps74]

Originally Posted by bigbrownbird

Hello,
i'm down from the 77-79 forum, but i have been working my way through college with oil changes, for the first 2 years doing them, and the last year just selling them. The reason ford went with 5w20 is because the clearances are tighter on these newer engines. My friend who is a service manager at a ford dealership informed me of that tidbit of info. If you use a heavier weight, such as 5w30 or heavier, ont only will it void the warranty, you take a risk of cooking your new engine! I agree, 10w30 is what i run in my old vheicles, but if I did have a newer ford, I'd make sure to fun the required 5w20. Most major oil brands have it on the market now.
I hope I helped you out.

Lee

Sorry, but if that were the case no oil would work, as tolerances cannot be that "close". If they were, you'd fry your engine anyway (ie. metal to metal). Once engines heat up, they need that viscosity to "cling" to the close tolerance parts (ie. rod/crank bearings). My wife's 02 went to the Ford dealer for the 5000 mile service, I told them to use 10w-30. They said fine. Don't want to start an argument with my first post, but do you do you actually think they would have used 10w-30 if it voided the warranty at a Ford Dealer??? BobG in VA

[macfrank]

Remember that you are using synthetic oils now a days. It is 300 times better than the old fashion 10W30. Besides unless you use Premium Gas and Synthetic Oil you warranty is void in many cars now a days.

Originally Posted by ajsam01

I noticed that my owners manual doesn't list any other weight motor oils as alternatives. That seemed odd to me. I know that Ford "recommends" 5W20 because it allows them to claim better gas mileage ratings. I'm not so sure I agree that oil so light can provide adequate engine protection. I grew up on 10W40 and relucantly changed to 10W30 in the 90s. Am I too old school? I'd really like to run at least 5W30 but not if it means voiding my warranty.