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Discussion Starter #1
My engine is coming back from the machine shop with new valves, valve springs, seat, and seals, new freeze plugs, and has been milled .010" total. My question is, which oil should I use?? I know that the factory spec is 5w-30, preferably synthetic. But which synthetic? Mobil 1? Royal Purple HPS? Amsoil?? So many options. What I'm wanting out of it is if I were to lose oil pressure again, that any residual oil left on the bearings would be slick enough and hold up long enough for me to either realize it, or for the oil to get picked back up by the pump and cycling again. I asked on Face-crack, and the result is highly mixed, including a few I've never heard of. It will be running slightly larger injectors, and a re-calibration, but other than that and the required milling, it will be stock.
 

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Virginia Gentleman
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I am not a big fan of synthetics, but Mobil 1 is reasonably priced (for a synthetic). Royal Purple and Amsoil are overkill if you ask me. Too pricey. Some will tell you Mobil 1 is not a true synthetic since it comes from Group III base stock. The oil purists will tell you only Group IV oils are true synthetics. For most though, Mobil 1 and many other synthetics made from Group III base stock are synthetic. Probably be more accurate to describe them as semi-synthetic.

I wouldn't have any problem using a good "regular" oil either. Even today's "dino" oil (not synthetic) are much improved over what was available just 5 years ago. My '06 Ram w/Hemi has 177K miles - all on regular non-synthetic oil changed every 5-6K miles. Still purrs.

Curious though - what was the cause of the oil pressure loss in your engine? Oil pump failure?
 

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Discussion Starter #3
Well Doug, unfortunately, I don't know what the cause was. I was going down an on-ramp, the engine 'hiccupped', which shook the entire car, then I noticed a knocking. Stopped, pulled off, towed it home, and found a bunch of silver in the oil pan, and #4 rod bearing spun and melted to the rod. It happened so fast that I never saw the gauge change, and I have no reason to doubt that it reads wrong.
 

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Any good major brand oil with the latest SAE rating should be fine, whether synthetic or not. Some people here advocate conventional oil during break-in, then synthetic, to ensure the rings seat properly.
 

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Part Connoisseur
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What kind of engine work was done to the block? You only mentioned what was done to the head. If you got new rings in the block then you definately want to stick with only conventional oil during the engine break in.

However, you need to remember that not one single brand of oil is "the best." That is why there is API and ILSAC ratings on your oil to ensure quality and uniformity across several different brands.
 

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Discussion Starter #6
The block had part of the total .010" milling done, freeze plugs replaced, new intermediate bearings, and a good cleaning; and yeah, I probably should have used the word "type" instead of "brand". So, I start with conventional for about 500-1000 miles, then switch to a Mobil 1, or just keep using the conventional. I am also thinking about using Z-Max in the oil as well, help get everything into the empty spaces in the make-up of the metal.
 

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When I rebuilt my engine in the turbo Z with a radical head modification, milling and other work, turbo rebuild, block boring with new bearings and rings etc....... I ran 250 miles on dino juice and have run Mobile One ever since.

I'm running either 5W30 or 10W30 depending on what I find on sale at Walmart.

It's time for a change now come to think of it.
 

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Virginia Gentleman
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msmart86_2000 said:
I am also thinking about using Z-Max in the oil as well, help get everything into the empty spaces in the make-up of the metal.
Additives not needed. Just use dino oil or synthetic that meets Chrysler specs. If Z-Max was so good, wouldn't the manufacturers use it? Think about it for a moment.
 

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Since the block was not bored nor were the rings changed it is fine for you to start using synthetic oil if you wish.
 
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