Oil for custom 351W motor

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Originally Posted By: 440Magnum
Originally Posted By: OVERKILL

Will a Mark VIII fan fit? If so, that, plus a DCC controller should be all you'll ever need. Those things move a STUPID amount of air.


I bought a MkVIII fan for my Polara, and decided it would be too much work to make it fit. So I risked going down in size to the fan from a 3.8 Taurus (considered second to the MkVIII fan among OEM fans) and it works great at keeping the 440 with AC cool along with a DCC continuously-variable controller. Why that much fan is needed for a front-drive v6, I'll never know. The only complaint I have is that the DCC controller generates a lot of EMI and actually interfered with my ignition system until I added a lot of ferrite chokes on the wiring. You could feel the idle get "choppy" as the fan ramped through certain speeds- not good. But a big electrolytic cap on the input, chokes on the input/output, and re-routing the wiring in the harness to stay away from the ignition fixed it right up.




Many early FWD cars had an excessive amount of stuff packed into a small underhood compartment. The radiant heat from the exhaust manifolds and other sources then became a huge problem. The manufacturers didn't do much to help heat ventilate out from under the hood of the car either. V6 engines made this problem worse.

This is why many early FWD cars weren't relaible, and why the paint on the hood often peeled away while the rest of the paint was intact. Many other things located under the hood didn't last long either. Mom's 1985 Nissan Maxima suffered the same problem.
 
OK, so there are number of things to think about. The way conventional oils are built, it is not 40 grade base stocks, but whatever the W rate is with VII's to get to the hot functional grade. So 10W starts with 10 grade base stocks and adds additives to get to 40 hot. Maybe a 20 grade base and pour point depressants to get the 10W rating and VII's to get to 40. Those additives are not oil, they are form of plastic. They do carry oil in the coiled chain structure, so that is why they work. But they are shear sensitive. That is why many XW-40's shear down to 30 pretty quickly.

Full synthetics rely on a different principal and the base stocks are often able to pass the W rating tests and still make the hot rating with few VII's. But, some of them have a low surface tension and drain off when sitting. That is not to say that they do not leave an oil film, but they may be bad at maintaining capillary fill when sitting cold. It's part of what allows them to get their low W rating ... So as long as you prime that engine after sitting, no harm. W/o the priming, it may clatter on cold start. If you hear that, change the oil to another formulation. Some ore more prone to do this than others ...

What you really want is a 30 grade oil if the bearing clearances are close to stock. That is the engineers yard stick when they set the design parameters. Your hot oil pressure sounds like you are right there. Since you don't drive it at less than 50*F, you really do not even need a W rated oil. That is for snow country. You could run that engine very successfully for decades on a good SAE 30 HD oil. Kinda old fashioned, but it always works. 100% oil and no VII's.

But, because of the odd track day, you are hitting the bearings pretty hard near redline, so maybe you want something stouter when hot. There are plenty race oils there. But there are some strong street oils too that work just fine. Valvoline makes VR1, but the also make other premium 15W-50 oils that hold up very well. I run them in high mileage Windors that clatter on cold start with wimpy syns. Always sound good and I get a bit more gauge hot.

With a 7 qt pan, you are not really stressing the oil chemically unless your carb is way off. If the tune is good, the pipes are not black, and your eyes never water - there is not fuel dilution. So I'd run whatever works best for a few years at a time. I'd do a UOA at the end of the season. If the results are OK, I'd just leave it and do it again next year. I would never run a built engine w/o a UOA here and there to know what is going on ...

Taken care of with that use, it may outlive us all
smile.gif
 
The OP hasn't logged on here since late 2017.
Good answer though.
My 69 GTO likes Supertech 10w40 HM conventional.
 
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