Worthwhile to switch present oil...or not?

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Jul 27, 2002
My 1996 F-150 now with 217K on the oringinal 302 V-8 has used only Motorcraft 15W-40 for the past 117K. From new to 100K I used Motorcraft 10W-30. Always used a Motorcraft FL-1A filter. My question is I have always changed my oil at 3K intervals up until now. I would like to start extending the drains to 5K or better yet 6K. Would the present 15W-40 be ok to use or do you guys think there would be a better oil to use. The truck gets the snot run out of it with heavy stop and go, heavy loads, dirt, dust, and lots of full throttle blasts. Never had the engine apart, not even valve cover gaskets. Any oils out there could do a better job with the extended drain idea?
I would recommend establishing a baseline first by doing an oil analysis with your current oil of choice (Motorcraft 15W40 in this case). It will at least give you an idea of your wear levels, and how well your oil is standing up during 3K miles. Then, you might want to read some more info on these boards regarding Mobil Delvac 1 5W40, Shell Rotella 5W40, Chevron, Schaeffer, & AMSOIL. Pick one that you feel comfortable with and run some analysis on it and compare with your baseline. You might want to also look at AUTO-RX, and see if that sounds interesting to you. Don't forget to post your results [Smile] Regards, Oz
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