300/4.9L vs. V8 factory recommended oil change intervals...

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1986F150six
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300/4.9L vs. V8 factory recommended oil change intervals...

Post #1 by 1986F150six » Fri Apr 13, 2018 10:30 am

The owner's manuals for my son's 1984 F150 and my 1986 F150 both state the recommended oil and filter change interval for the 4.9L engine to be 7500 miles. Under the same conditions, the V8 interval is 5000 miles. I wondered why?

Here is what The Frenchtown Flyer had to say:

Originally Posted by The Frenchtown Flyer

That's a good question. I can think of two reasons. The six oil pan holds six quarts and the V8 holds 5. For the oil to get contaminated / depleted in a six quart fill it would take longer. Second reason - with a six you get about 3/4 as many firing events, so less combustion by products. Trust me, these things aren't arbitrarily decided. Only after extensive dyno and vehicle testing. Hope this helps.

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B RON CO
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Re: 300/4.9L vs. V8 factory recommended oil change intervals...

Post #2 by B RON CO » Fri Apr 13, 2018 1:52 pm

Hi, I would never follow the book on oil change. My daily drivers go 5000 miles between oil changes, and my weekend cruisers get an oil change every year, even if they only drive 1000 miles. I stay with premium name brand oil. Good luck
B RON CO. Still workin' on it!

1933 Ford Pickup - 59A Flathead V8
1966 Ford Bronco - U14 - 170/200 Straight 6
1966 Ford Mustang - 289 V8

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Re: 300/4.9L vs. V8 factory recommended oil change intervals...

Post #3 by Harte3 » Fri Apr 13, 2018 3:35 pm

'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

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