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Which motor oil weight do you use on a 351?

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Old 02-24-2004, 04:22 PM
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Which motor oil weight do you use on a 351?

I recently purchased a ’96 Ford Bronco with the 351 engine. It has about 88,000 miles on it and runs really great. I want to change the oil on it but I’m undecided on what type to replace it with. According to the manual, the recommended weight is 5W-30 (at least that’s what I think I read) for the 351 engine. I’ve always used 10W-30 on my ’91 F-150, but then again, it’s only an inline 6. Do ya’ll agree with this recommended oil weight? What’s the most popular brand used? On my ’91, I’ve always used Quaker State and recently switched to the High Mileage type – it has about 180,000 miles on it.

I also have a slight concern with something I think may be coming from the transmission. At take off, I feel a slight jerk, almost as if someone tapped my bumper from behind. I also feel this when I’m slowing down and about to stop. Is this normal or should I be concerned? It performed flawlessly during the 250 mile trip home when I purchased it.

Thanks in advance for any input.
 
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Old 02-24-2004, 05:02 PM
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Down here in TX I've always used 20W50 due to the heat. It was recommended by a mechanic buddy of mine a while back. I've never had any problems, and it boosted my oil pressure a bit.
 
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Old 02-24-2004, 06:08 PM
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My 88 5.0 manual says to use 10-w30. It gets hotter then heck here too and I use 10-w40 in the summer. I used to use 20-w50 but if I let my truck set for a couple of days I hated to start it cold with that thick of an oil in it. Most engines in the 90's and up recomend 5w-30 because they are built a little tighter. If it were me I would just go by the manual.
 
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Old 02-24-2004, 08:42 PM
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If it were a lease vehicle, I would follow the recommended 5W30 because they foot the repair bills. Look at it this way...

5W30 is lighter/thinner- after warming up, it starts to thin out more. The hotter the oil gets, the faster it breaks down too. And when oil doesn't protect as it should, goes the motor! As we all know, engines don't like being HOT and lightly lubed!!

In this part of TX it gets HOTT in the summer, and not all that cold in the winter. 20W50 may be too thick for really cold winters, but going with the 3000mile oil change, you can always put 10W30 in for winter...

Like I mentioned before, it boosted my oil pressure too. I was using 5W30 and with my "loose" bearings I had 15-20psi at startup, dropping to 1-3psi hot. Now with the heavier stuff I have 30-35psi at startup and 10-15psi hot. So I know oil is circulating pretty well with the heavier weight oil.

Just my 2¢...
 
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Old 02-25-2004, 08:42 AM
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I'm in south central Texas so I do understand HOT! Thanks all for your replies. I certainly appreciate the responses.
 
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Old 02-25-2004, 09:21 AM
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I use Chevron Delo 15W-40 all year in Southern California. Temperatures here range from the upper teens here in the mountains right now to over 100 down in the desert in summer. 15W-40 is heavy duty "fleet" oil sold in gallons for diesel and gas trucks. It has more detergent/dispersant and ZDDP anti-wear additive than passenger car oil. Pennzoil LongLife, Shell Rotella T and Mobil Delvac are other popular fleet oils.

Jim

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Old 02-25-2004, 09:51 AM
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I also have a slight concern with something I think may be coming from the transmission. At take off, I feel a slight jerk, almost as if someone tapped my bumper from behind. I also feel this when I’m slowing down and about to stop. Is this normal or should I be concerned?
This sounds like the take off/stop clunking that has been discussed many times in this forum. There can be several things that cause this, but the most common cause is the slip-joint on the rear drive shaft. All you need to do for that is slide the rubber boot to one side and grease the slip joint. Should take care of that problem. It did on mine. Use the search tool to find more discussions on this.
 
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Old 02-25-2004, 10:26 AM
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15W-40 is heavy duty "fleet" oil sold in gallons ...
Sounds pricey. Is this stuff expensive?
 
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Old 02-25-2004, 10:28 AM
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This sounds like the take off/stop clunking that has been discussed many times in this forum.
Thanks, I'll do some searchin'.
 
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Old 02-25-2004, 08:06 PM
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It is not bad at all. I used to have a diesel and that is what I used. Maybe like 8 bucks?
 
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Old 02-26-2004, 09:07 AM
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Originally posted by cueman
Sounds pricey. Is this stuff expensive?
No, it is inexpensive since an oil change on a diesel takes several gallons, not quarts. $6-7 a gallon is what I pay. That works out to $1.50-$1.75 a quart.

Jim
 
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