5W30 or not
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Junior User
Joined: Jan 2003
Posts: 82
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From: Louisiana
5W30 or not
The owners manual for my 98 F150 4.6 says to run 5W30 motor oil only, no matter the ambient temperature. I asked one of the dealership mechanics who is a friend of mine why such a light oil he told me that Ford says the tolerances are very close and need a thinner oil to properly lubricate. My question is can I go to a 10W30 after 40,000 miles? I live in central Louisiana and its pretty hot here in the summer.
Postmaster
Joined: May 2002
Posts: 3,028
Likes: 1
From: Annapolis, Maryland
5W30 or not
I don't really see the problem - after 40K, the motor's pretty well worn in. I've always been told that 5w30 and 10w30 are pretty much interchangeable in hot weather. However, like your friend said, the tolerances are pretty close - I'd run 5w30 in the summer, and then send it in for analysis. If it seems like it's getting clobbered (I'm not sure what indicates heat damage with motor oil), then I'd try the 10w30.
Good luck!
XXL
Good luck!
XXL
Postmaster
Joined: Jul 2001
Posts: 4,038
Likes: 3
From: South Kitsap County, WA
5W30 or not
You want to stay with the 5W-30. The thinner oil may not stay up in the engine oil galleries as long, but when you start the truck it'll get there quicker (think Mobile 1 commercial). The lighter oil has better flow properties in the colder weather. After using the right weight oil for 40K you probably still have some pretty tight tolerances that will need the lighter oil. During the summer the heat outside has a different effect on the temp in the engine. That oil is already at 30W at operating temperatures and won't cool down as fast during the summer so it'll be thicker longer and stay in the galleries and coat parts thicker, just like the 10W-30 would. The lighter oil will be quicker to get in the tolerances than the thicker stuff.
If you swap, then you should do an engine flush to get rid of the lighter weight oil. I can't recall for sure why that is, my dad just always said they don't mix well because the polymers were different. It made a little sense to me in organic chemistry.
All in all, it depends on how you look at it. If you're over the warranty period you can do what you like. The swap may not do you any good and cause other headaches.
-Kerry
If you swap, then you should do an engine flush to get rid of the lighter weight oil. I can't recall for sure why that is, my dad just always said they don't mix well because the polymers were different. It made a little sense to me in organic chemistry.
All in all, it depends on how you look at it. If you're over the warranty period you can do what you like. The swap may not do you any good and cause other headaches.
-Kerry
Elder User
Joined: Nov 2002
Posts: 736
Likes: 1
From: Texas, USA
5W30 or not
Stay with the factory recommendations, period. Here's why.
I've used only 5w-30 for all of the last 108,000 miles in my '97 Expy 5.4L, 4x4. It consumes no more oil now than it did at 15,000 miles, which is a quart in 5,000 miles. This in spite of towing a 5,000 lb trailer up 11,000 ft moutain passes numerous times, with long stretches at 4,500 rpm. And considerable offroad driving in the desert heats reaching 115 degrees F. in CA, AZ, NM, and TX. My Expy has never overheated and doesn't show any sign of wear. I change that easy to reach oil filter every 2,500 miles and the oil every 5,000 miles.
One time around 60,000 I tried a pint of Slick 50 because a friend had it left over from his job, and told me it wouldn't hurt, and might do some good. The first time I cranked it up the valves got noisy. AS soon as I drained it out and put in fresh oil, the noise went away and didn't come back. Those are very tight tolerances in the Triton engine, which is one reason you can rev them up all day long and not break anything. Year round, stay with the 5w-30 or the new synthetic 0w-30
Hope this helps.
I've used only 5w-30 for all of the last 108,000 miles in my '97 Expy 5.4L, 4x4. It consumes no more oil now than it did at 15,000 miles, which is a quart in 5,000 miles. This in spite of towing a 5,000 lb trailer up 11,000 ft moutain passes numerous times, with long stretches at 4,500 rpm. And considerable offroad driving in the desert heats reaching 115 degrees F. in CA, AZ, NM, and TX. My Expy has never overheated and doesn't show any sign of wear. I change that easy to reach oil filter every 2,500 miles and the oil every 5,000 miles.
One time around 60,000 I tried a pint of Slick 50 because a friend had it left over from his job, and told me it wouldn't hurt, and might do some good. The first time I cranked it up the valves got noisy. AS soon as I drained it out and put in fresh oil, the noise went away and didn't come back. Those are very tight tolerances in the Triton engine, which is one reason you can rev them up all day long and not break anything. Year round, stay with the 5w-30 or the new synthetic 0w-30
Hope this helps.
