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Looking for some input on brand of oil to use, as well as filter. My ‘61 has 92,000 original miles on it. 394 4bbl carb. I have been using 10w-30 Castrol. Any reason to switch oil weight? Any brands that you recommend for this engine and this mileage? Filter?
The new oils are no longer formulated for flat tappet cams.
They removed a lot of the zinc (ZDDP) content (a good anti wear additive) due to it causing damage to catalytic converters.
These oils are made to protect flat tappet camshafts and still contain the necessary ZDDP for protection.
Valvoline VR1 racing oil is also very good.
You do not likely need a different viscosity unless you have oil pressure issues.
With a worn engine you may pick up some oil pressure with a 10w40 or even a 20w50, but not for any real performance benefit on a stock engine.
Living in MN, I'm not sure if you are running this vehicle in the winter, but thicker oils do not flow well in the cold.
I run the 10w30 VR1 in my 64 394 with 100K miles.
Last edited by Lonnies Performance; February 11th, 2024 at 06:05 AM.
I've always had luck running Rotella T4 15W-40 in my Oldsmobiles and I run Wix filters.
Beware that a lot of automotive parts on Amazon are Chinesium and rebranded. I'm done ordering parts from Amazon, from now on it's the auto parts store, or online specialty suppliers (Rock Auto, Summit, etc.) for me.
There is exactly ZERO reason to change oil weight from what the factory recommends. If you've been using Castrol with no issues, then continued use is unlikely to cause a problem. The cam and lifters have long ago broken in. If zinc levels cause you to lose sleep, then use one of the high-ZDDP oils with the same weight. More viscosity just increases internal friction and HP loss.
Thank you all for the suggestions. I’m a bit of an overthinker when it comes to the Olds. KISS….keep it simple stupid. No driving in the winter for me here it is stored in the garage until it warms up.
Shell Rotella T 10W-30 and 15W-40 has 1200 ppm ZDDP. This info is directly from Shell about two months ago.
Joe, I've never heard that ZDDP levels are only important during break-in on flat tappet cams. I thought it was important for continued use and haven't heard anything to the contrary, have you?
The ZDDP is nice to have in an older motor, but I've run plenty of flat tappet motors on regular low-ZDDP oils with zero issues. The reality is that brand new parts that haven't worn in tend to have localized high spots on the machined surfaces. These can push through the lube film and initiate a metal smear, which is a cascading effect. Once the lifters and lobes are broken in, this is a very low likelihood event. For cars I care about, I do use Amsoil Z-Rod, but again, in 10W-30 or 10W-40 weights, depending on the application. And yes, on well-worn motors with large bearing clearances, I'll use the 10W-40.
February 10th, 2024, 11:32 PM
