I have a 86 f350 7.5 c6. 17000.0 miles
I have been using Chevron 20/50 Supreme oil for 20 plus years. My Chevron distributor says this product will not be readily available any more. I have people that swear by Mobile One. My concern is changing to synthetic oil with the millage I have on this engine. I have no oil leaks and excellent oil pressure. All comments are appreciated.
Thanks Rodger

 

I'm a proponent of using diesel oils in older (and some newer) gasoline engines. I will not claim to be an expert but diesel oil is high in detergent additives and zinc, which our older engines like. I run Rotella products exclusivly in all of my vehicles, 15W/40 dino in my 85' F350, Land Rover and diesel truck, 5W/40 synthetic in my Turbo Subaru. I have read that the zinc may damage catalytic converters over time, I have put 80k miles on my Subaru using synthetic Rotella with no issues.

To answer your question on transitioning to synthetic, I have done it on a few high mileage engine with no issues, YMMV.

 

chevron 15-40 is still readily available, anything wrong with using that instead?

 

The only thing I don't like about Chevron 15W-40 is it burnt in everything I put it in. My favorite diesel oil is the Mobil Delvac 1300 Super 15W-40. Available at any Walmart I've ever been to.

 

... diesel oil here.
Usually 15w40 Rotella T3, synthetic 5w40 T6 in the depths of winter.
Wait for sales at Walmart or chain stores.

 

I've been running the 15w40 diesel oil in my truck for years. Naturally, I will continue to run it after swap, just have to buy twice as much per change......

I do use synthetic in both the 95 B2300 and 02 Focus.
Most newer oils lack the ZDDP additives needed for a flat tappet cam, this includes synthetics like Mobile 1. This is why so many people are running "diesel" rated oil, as they have much higher levels of these additives.

 

I Have never used synthetic on any of my trucks, rottela 15W-40 works fine for me and that is what i will stick with, I service my truck every 5K, and with over 250,000 on the clock I think she just broke in. I'm less picky on the filter, what ever I can get on sale or through bulk purchase, Motorcraft, Fram, Puralater havn't had a problem with them at all, I use Baldwin for my coolant filter and they work very well, I will be running those as long as I keep the filter in my truck.

 

can get hundreds of answers on this. Me personally I just run what is recomended weight wise.

My 56 calls for straight 20 weight so I run 10w30, lots tell me to run 20w50. I shy away from multi weight oils that have that large of a gap, the oil wears out quicker than one that doesnt have that big of a gap.

In my 351W I run 10w30, and my 302 I run 10w30.

As far as diesel engines goes, id run Rotella T, thats all we use at work when it comes to diesel engines. Now as far as running it in gasoline engines, I personally wouldnt because theres good evidence that exposure to diesel oil can have a strong influence on you having cancer later in life. I am around it enough as it is at work, wouldnt want to mess with it in my personal vehicles as well.

Brand wise, ive shyed away from Pennzoil motor oil and I strictly use Vavoline. I dont know what I will use on my '56, I thought of getting the Syntech from Castrol but I dont like the 20w50 weight. So i will probably run Vavoline 10w30 with a bottle of zinc additive added to the oil. For the oil bath filter I will probably run cheap Pennzoil for that.

 

Multi-viscosity oils lose their viscosity range with wear. The reason is that long polymer chains are used to increase the range and those chains get broken during use. And the wider the viscosity range the longer the chains so they get sheared easier. That doesn't mean the oil is "worn out" but just that it isn't as good as new. It still lubricates well and the detergents should still be working, just in a more narrow viscosity range.

 

ditto here considering trying chevron though.

 

That is what I am talking about. Personally Id still want the oil to be the weight it is and when hot it lubricates like the heavier weight indicated.

If its 10w30 I want it to be 10 weight oil that operates like a 30 weight oil when hot at 3,000 miles, like wise id want a 20w50 to still be a 20 weight oil that operates like a 50 weight oil when hot at 3,000 miles.

Sure it probably doesnt change anything as the oil breaks down but it loses the ability to lubricate like the thicker oil when hot and that to me is a concern.

 

I want to thank everyone for their input, I hope it will help others as well as myself. I am going to go with the Rotella 15/40.
Rodger

 

I would if I found it or Delvac on sale in jugs.
I'm not invested in Shell.
I just don't want to spend more on a quality oil change than I have to.
I also don't want to sit on a drum to save a buck or two each time.

 

Jim, does your local Walmart not sell Delvac? mine does, as does every Walmart within 50 miles of here. It's actually a little cheaper than Rotella. I'm pretty done with Rotella, after my truck would randomly burn 1/4 at a time out of nowhere. Doesn't burn Delvac at all. I'll use the SAE30 Rotella for lawnmowers, but that's about it. You can always ask your local Walmart to start carrying it. I've done it before with certain things and they started stocking what I requested.

 

I would just skip the synthetic, save your dough and use any name brand 10-30- or 40 dino......remember, it's a 28 y/o truck.