Now low ZDDP motor oils are far superior and reduced ZDDP (to protect the catalytic converters on new cars) isn't that big an issue. If you are worried then it's simple, just change your Corvair oil every 1,000 miles before the oil starts to deteriorate. Any name brand 10W30 oil will be more than adequate IF you change it before it wears out. Since most folks don't drive their old hobby cars that much it's not a big deal to change oil at 1,000 miles. If you are driving your Corvair a lot and don't want to change oil at 1,000 miles a higher ZDDP motor oil might be worth it. As far as the "Diesel" motor oils go, even those now have lower ZDDP because of new emissions control, but again diesel motor oil, like gas engine oils, is now far superior to anything sold in the 60's even with lower ZDDP.
The exception is new cam shaft break-in. Always a critical period and the use of camshaft break-in lube and a higher ZDDP oil will reduce the possibility of new camshaft failure. That said flat tappet camshaft break-in has always been a critical period, even with higher ZDDP oils. Once a camshaft is "broken-in" simply keeping the oil clean with frequent oil changes will ensure a long life.
All this information is in the SAE oil papers describing using ZDDP to compensate for motor oil surface tension break down as the oil ages. Not as critical with the superior motor oils sold now.
About synthetic motor oils. Most motor oils are partially synthetic now. The only advantage of a full synthetic motor oil is the ability to tolerate higher temperatures encountered during "hard" driving or racing. They get just as dirty as standard motor oils so they offer NO advantage unless you are racing or driving under hard loads like towing in high temperatures. Contrary to the hype they need to be changed just as often as standard motor oil during normal driving.
Unless it is brand new engine I'm breaking in or I'm running very stiff valve springs in a performance engine, I worry very little about ZDDP levels and certainly never ever use any additives. On my beater Corvairs I run whatever 10W30 or 10W40 is on sale and have done that for years. It is still way better oil for these engines than they were fed back in the 60's and 70's. I've never wiped out a cam or had oil pressure issues.
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5
- Corvair of the Month
- Posts: 272
- Joined: Wed Aug 08, 2012 9:45 am
- Location: North Shore, MA
Just for chuckles, obviously.
Since when do Corvairs not run high temperatures?
Send your oil out for analysis. Unless you are changing it every 750 miles good synthetics have huge advantages.