I've got my factory original 1978 Chevy 250 with less than 45k miles on it, with no major changes yet. This is a street car and driver. I've relied on the manufacturer recommendations and based on the climate of midwest, I have been filling it with synthetic 10w-30 every year. I don't drive it when it is below freezing here, and our summers are generally mild with only the occasional day in the high '80s or low '90s. According to the chart in the manual, it can use 10w-30, 10w-40, 20w-20, 20w-40, and 20w-50. With 5w-30 only if I used it during winter and the cooler season before changing it.

But newer cars I've owned have just recommended 5w-30 and that's it. This obviously isn't the same 5w-30 from 1978, so I don't know if this chart still applies these days? Is 5w-30 still too thin to run in an engine of this vintage in temperatures over 60 degrees anymore?

I would not use a 5w anything oil in your 250 or mine. 10-30 at minimum. I also add a 1/2 jug of GM EOS at oil changes for the cam.

I agree with tlowe on the super light (fuel efficient) formulations. The base oils are to light for older engines. I find the writings of Chris Longhurst instructive: Car Bibles. The article is a bit lengthy but worth ones time.

Highlights specific to older engines - avoid xx-30 in favor of yy-40 where y=10 or higher. Also avoid oils rated higher then CF because downward compatibility cannot be assumed as the CF testing regimes are no longer performed.

THIS +1,000

How much ZDDP does 8oz of EOS add to 5.5qts (using the 1qt filter instead of the 0.5qt) add to 800ppm ZDDP oil?

I should note that the Valvoline VR1 synthetic (black bottle) API SL 10W-30 I use is tested at 1100 ppm ZDDP.

I haven't found any official GM pubs (like an MSDS) that document ZDDP content. There's an interesting article over at the SlantStix website which suggests some fairly precise measures of zinc and phosphorus content in EOS. It also gets into the arithmetic involved in using EOS in order to 'top-up' the ZDDP levels in a given oil formulation.

The article also contains some broken links into the SAE website. Fortunately a google search on SAE and the corresponding paper number will get you to the new location - e.g. "SAE 831760".

Update: I found a working link to an older image of the MSDS for EOS over at the VR6 racing site. It dates to '89 and shows that GM was using Lubrizol's ingredients - with ZDDP at 5% by weight.

Thanks, more reading to do. I got my spring grease and oil coming up, and I'm shopping for the best deal on the oil and filter. Found the Wix 1qt pretty cheap locally and a deal on Valvoline grease that meets GM specs, just picking an oil now.

If you're talking Valvoline make sure it's VR-1.

I wouldn't even use that. There's several oils out there for older engines. I used Brad Penn oil and it did very well. Modern oils have too much bad crap and not enough good crap to work well with our old engines. I wiped a cam that way. Local machine shop stocked Brad Penn and swore by it so I started using it instead and only resorted to VR-1 (and ONLY VR-1) when I couldn't get the good stuff and needed to top off. VR-1 is the most common of the types of oil you need but, again, I still wouldn't rely on it alone.

Last time I changed, I found VR-1 synthetic (black bottle) cheap. But I've been Googling it and the synthetic seems hard to find in store now, and the conventional (silver bottle) is not that cheap. My innards are still factory stock with weaker springs and low lift, that was already broken in with 1978 oil. The oil needs are not as demanding as a built engine. Over $60 for just the oil in an annual change is a bit much. I think I can find something more reasonable as I keep searching.....or at least a sale.

Brad Penn is good oil!! It is what used to be Kendall Nitro before Kendall was bought up a few years ago. My Harley Mechanic recommended it for my old Shovelhead!! No problems that I've found since using it!!

Brad Penn or Valvoline Racing VR1 10W30. Brad Penn makes break-In oil too, used it on my 230 build. I've been using Valvoline rcing for many many years on flat, solid lifter engines. (Aircooled VW). Most of the racing crowd back home swear by it.

But $60+ an oil change just for the oil. $$$$$$$$$$$$$$$$$ I got the Valvoline VR-1 a few years back for a little over $4 a quart with tax locally. I'm pretty sure there are good oils for a lot cheaper.

The zinc being removed for the oil back 12 or so years ago was part of a big push to rid the streets of these older cars. Just like the "Cash for Clunkers" programs most all states pushed to encourage people to trade them in so they could be destroyed and not put back on the road. Now the gas being alcohol based is just another step to make it harder for older engines to survive the advancing technology that is biased towards the computer age cars. Products like these oils will only get higher as fewer and fewer of the cars needing those products keep disappearing. They know what products to target to cripple older engines, first it was the oil and now the gas. It wouldn't take many more changes to disable the older engines for good. What will happen when manufacturers quite making bearings and simple rebuild parts because the demand is so low as a result of the costs required to find the oils and gas needed to run them.

Quaker State Defy High Mileage 10w30 API SL - 1221ppm Zn - $27 for 5qts

You might find this blog interesting. The very first (highest rated) conventional oil? 10W30 Valvoline Racing VR1.

https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

Yeah, I'm currently reading it....very loooong. What I got so far is pick an oil that he has tested and has higher than 90,000psi for stock (mine so far), 105,000psi for built, change oil every 5000miles or yearly, and for cold starts take it gentle for the first 10 to 15 minutes. Kind of challenging the conventional wisdom of viscosity ratings and ZDDP levels.

I know I've found Valvoline VR-1 cheaper in the past, maybe it was on sale, but I think it was maybe $4 a quart? I can't seem to find any that cheap locally now?

Can't really comment on what oil is best.
But I found this:
https://www.facebook.com/pg/penngrade/about/?ref=page_internal

Might be easier to find 'Brad Penn" if you look for the new labeling.

Pete

The topic of oil shear stability testing has come up before: Inliners Tech Tips circa '17 the Street Commodores testing gives the highest marks to Royal Purple and Penrite.

For me the most interesting take away when comparing modern motor oils is the primary objective that seems to be at play: extra long service intervals - 7500 to 10,000 miles in some cases. What hobby car is subject to such treatment?

Through the years the chemists have been trying to engineer oil additive packages that last longer and longer.

However, the chemistry in the zinc phosphate compounds used in motor oils reveal that the most effective ones are the least thermally stable - causing them to be used up (primarily at the edges of the compression rings). This leads to the need for a service interval built around zinc phosphate depletion - not oil cleanliness.

Taking us back to the old adage - "the best oil for your hobby car is fresh clean oil . . ."

Based on what I have read it isn't quite that sinister . . .

It is curious what is actually 'at work' with an engine oil's ZDDP content. It turns out that it is not the ZDDP that provides the wear protection but the deposits left by the thermal break down of the zinc phosphate - Ferguson, Johnson, Gonzales, Hobbs, Allen and Williams

The problem with the deposits is that they also accumulate on the surfaces of the catalytic converter - causing the unit to become less and less efficient - eventually failing emissions testing. So ZDDP levels have been declining in response to effect on emissions equipment (on which the government mandates extra-long warranties from the auto makers).

I saw in Hot Rod magazine back in the late 70's several times that they were warning of legislatures wanting to pass bills to get hot rods and old cars off of the road back then. Might not happen entirely in our lifetime, but more has been done in the last 10 years to move in that direction than from the early 2000's back to the late 70's when the articles were written. A lot of manufacturers have also discontinued parts for some engines, like the Slant 6, which I think is equally as popular as the Chevy and Ford 6's. In other countries like Oz and South America, these engines are still real strong, because they haven't been squeezed out of the market by V8's, so they may last considerably longer in those areas.

I have been using the Brad Penn (now PennGrade1)for the last couple of years. Used their break in oil for the 261 motor with the 302 GMC rods and the Schneider flat tappet cam. Broke in perfectly, runs great, good zinc and additive package, and the oil clings to the rocker arms over the winter.

When I last bought it (about a year ago) it was like $6/qt. I think you need to find a different supplier because I doubt you have a 10 qt sump...

The Brad Penn they are suggesting is $10 a quart, not the Valvoline VR-1. Where is it you are seeing 10w-30 or 10w-40 VR-1 for $6? I can't find a supplier of it for that cheap, but I know I've gotten it cheaper than even that in the past. But a 4.5qt crankcase with a 1qt filter is still $36 plus tax and shipping if any, which is not all that cheap either.

Wow after reading this thread, made me nervous. I used Pennzoil 10w/30 in my 250. I did add Rislone ZDDP additive. Dont know if that additive is any good or not.
I did see a parts store about 5 years ago somewhat close to me with Brad Penn signs in their window. Im thinking if they're high in ZDDP I may grab some.