Packard Forum Index » V-8 (1955-56)

Best weight for mid to high temps?

for years and years the rule was no synth in any older engine due to the rope rear main seal. I use sae NON DETERGENT straight 30 wt oil 5 qts + 1/4 to 1/2 qt of lucas eng oil additive, changed once a year on the limited use classics and 89 octane fuel with lead substitute and a splash of marvel on fueling and have had great results on unmodified original engines. I dont drive vintage cars in the dead of winter so I see no need for multigrade oils. make sure the cooling system is full to the top and wire the exhaust crossover closed on these vehicles when used in the summer heat!

I use Brad Penn oil. Price not bad, depending on vendor.

I just bought 8 quarts of detergent 30 weight Valvoline Conventional. I don't know what they mean by "conventional" but the spec is "Exceeds API SN/SM. I don't really know what that means, either, but I don't see "synthetic" anywhere on the bottle. It was $46 bucks, $5.79 per quart, which is about the going rate for oil around here.

Yes, I am concerned about synthetic oil in older engines. One of the reasons why it tends to seep is that (so I've read) all the molecules are uniform sized, while conventional oil has a non-uniform molecular structure which tends to find a way to seal up small leaks. I think all that scientific-sounding jargon just means that if synthetic oil finds an opening the size of its molecules, it will just keep leaking through, while the conventional oil will eventually plug it.

Or, as I was once told: "Crud is a good sealant." And synthetic oil, as we all know, isn't as good at making crud.

If your talking about a fully rebuilt engine hot tanked and totally cleaned OK but I think there is another issue with older engines. There is almost assuredly crud in the rocker shafts,oil galleys around the rope seals etc. It is best to let sleeping dogs lie. running detergent or synth will break down the old grime and send it through the oiling sys and these are bypass filtered systems so most of the debris will go straight to the bearings causing issues. The theory is to use non det. so as not to start breaking this stuff loose and the limited miles we drive these cars it will be ten or twenty yrs of driving before you have to worry about adding to the sludge buildup with the conv, non det oil. If your already running a synth or det. oil in a 40,50 year old engine, ?

My 327 doesn't have an oil filter, so no problem there. I think one of the main things is, even if they are driven very little, change the oil every year or every 2K miles or so, and you should be all right, synth or no synth, detergent or no detergent. So what if you add a quart or two between changes? The only thing suffering is the garage floor, probably, unless an oil line actually does plug, which is unlikely with the old, basic tractor engines. (I know that's blasphemy, but I drove a lot of old tractors back in the day with flathead engines and no oil filters, and I know a tractor design when I see one.) The V8s are a different story, with different issues, but this thread was kind of a general topic so I thought I could make a general observation on it.

Don't know what is happening in the rest of the country, but here in Las Vegas, at the local Auto Zones, and O'Reillys in the past several weeks, conventional oil is just about gone. Over the past 20 years or so have been using 20-50 Valvoline Racing oil. Which along with the rest around here is gone. So if I change to synthetic, with some Zddp and Marvel, is should the viscosity be the same? Looks like somewhere around 30 weight should be ok. Maybe 40? What you mention now, that scares me the most is the leaking of the rear seal. One of my cars is a 40 super, which has the largest and least support for the rope seal in the rear. Several years ago changed the rear seal, and had to do it three or four times before it stopped leaking. If I change to synthetic may start to leak again. Thanks for all the input.

I'm still a little mystified, too. Is Valvoline "Conventional" which is available here, a non-synthetic oil? As posted earlier, it is specced as API SN/SM. I don't know what that means.

As far as what's available in other states, that seems to be all over the map. Heh heh. Lame. If I find out any more, I'll post, but someone may already know how to find out what's available where and what specs to look for.

I've had good luck with Valvoline in the past. I don't see anything wrong with using a multi-weight, but I use straight 30, and still add some MM oil.

The thing about having that thinner oil on starting is to get lubrication moving through the engine quicker. The thing about using MM is that it adds viscosity strength (at least claims to), and will leave a thin coat of oil on everything, also making startups a little easier on the moving parts.

As we've heard over and over again, much of the wear on an engine occurs at startup.

Something else I have against synthetic (as opposed to the synthetic "blends" (of which we have a lot around here) and the old conventional oils, is that straight synthetic gives very little rust protection when an engine is sitting for long periods. It's so slippery it literally slides off the parts and, depending on conditions, the insides can start to rust. NOT good.

I'm not concerned too much about the oil change I'm doing now... it's really going to just be a "flush" and changed fairly quickly. At some point, maybe next year, I think I'll try that Lubriplate stuff at the link offered earlier. Even with shipping, it'll cost about the same as the Valvoline I just bought.

This is the non detergent.

Attach file:

---

  (37.69 KB)

Don't understand why anyone would still want to use non-detergent oil??