1ow-30 Amsoil ZROD and Wix filter. I've been running Amsoil in my Powerstroke, Harleys for years, now in my 76 Skylark with a 68 350 flat tappet cam
Based on my own personal experience, I do not recommend using synthetics in an old engine that has had dino oils previously. I tried synthetics when I first got my Electra and they did a nice job cleaning all the gunk holding gaskets together, so the engine developed several leaks from different points. Keep in mind that was like a 5W50 or something like that so quite thin, but (after changing some of those gaskets) I've gone back to dino oil. Again, I'm sure others have had different experiences, just providing my own! I would not hesitate using synthetics after a new engine build or if the engine was resealed with new gaskets.
Synthetics oils & the crank seals are a leak waiting to happen. Unless you got one piece rear main like the 86+ SBC. Synthetics oils in a LSD rear end is not a good idea either. It won't let the LSD additive do it's job.. Thin oils like 10W 30 Im not willing to give that a try. Strait Dino 30 Ok. I run strait Dino 40 or 20W50. VR1 Realistically the the pan and main seal are real easy to change out in a Car or Truck.. Not a Boat..You pull the motor out... When these motors were made the was no multi weight oils.
The only synthetic oil I've ran is in my pop's 70 big block 4speed Royal purple 10-30 for 20yrs and it is the driest engine I've ever had it sits for months at at time and NEVER leaves a drop. My engines generally are leak free but his is ridiculously clean and dry, so I cant complain about synthetics ability to stay behind the seals
Please be aware that the only certain difference between a 10W-30 and a "straight" 30 is that the first oil was actually tested at the lower temp spec and given a W (winter) viscosity rating.
Multi-weight oils have been around for a long time, at least since the sixties. I'm not old enough to remember any further back than that... :^)
Wasn't the zddp additive being removed from oil because it caused problems with the catalytic converters?
This was true for me as well. I used to use dino all the time on a newer crank seal. Never had a leak. Bought synthetic one year because it was on sale and the rear main leaked like crazy. Peppered up my driveway and garage floor. Swapped it out for dino oil and leak stopped. I'm sure the crank has some wear around the seal area from all the miles but the synthetic was just too slick and found it's way out.
Precisely. In the last 10 years or so, a mandate was put forth to make all cat converters have a 100k mile lifespan, and the only way to do that was to drop the ZDDP content of the oil, if not remove it completely. I run nothing but synthetic in every vehicle I own. Just did the oil in my 67 last week. There was a little bit of seepage on the front/rear of the oil pan, but nothing that didn't wipe away with one pass of the shop rag. Not unusual after 5k miles to see a little bit there.
It's my understanding that the amount of ZDDP in modern oils has been declining because almost all modern automobile engines now have roller lifters. Since there is no sliding contact between the cam and lifter, the pressure on the cam is lower and the anti-friction properties of ZDDP are not as necessary. There are still a lot of flat-tappet Diesels out there, so Rotella - which is primarily marketed to Diesel operators, has a lot of it.
Fifteen or so years ago, Motorcraft catalogued a 10w30 and 10w40 oil that was specifically for older gas vehicles; the data sheet and bottle said not to use it in vehicles with catalysts. The ‘Chemicals and Lubricants’ catalog explained that it had high levels of zinc and if the rings were worn the blowby would kill the converter. Patrick
