For 23 years I have changed the oil in my Series 80 in February using 30 weight. For the first 15 years or so exclusively Quaker State but have used other brands in the last few years. A mechanic for a nice Antique Collection in Atlanata recently told me they use 10w-40 in all their classics. I know the 30 weight has served me well but would apreiciate hearing some members views on the subject.
I have two Series 80s, one (the sedan) whose engine has never been rebuilt and still has its original iron pistons, and one (the coupe) whose engine was rebuilt 11,000 miles ago with modern aluminum pistons in the 1980s.
I live in the San Francisco Bay Area where it never drops below freezing in the garages.
In the “looser” engine (sedan)I use my remaining stock of 20W-50 API SL oil, which has significantly more ZDDP than today’s API SN oils.
In the rebuilt engine (coupe), I use diesel-grade 15W-40 oil, either Chevron RPM Delo 400 or Shell Rotella (the latter is said to have a greater amount of ZZDP). For both of these, I find the best prices at WalMart or other mass retailers. Diesel-approved oils are authorized, by law, to have substantially more ZDDP than the current SN gasoline engine oils.
In all cars, I change the oil HOT at least once per year, usually in the fall. Detergent oils lose their detergency by oxidation over time as much as by mileage, so I believe it’s necessary to change the oil at least once a year irrespective of how few miles I’ve driven.
This is a complicated issue which has been addressed many times on the Message Board and in the Service Bulletins in recent years.
The foregoing is not intended to be a comprehensive review of the subject, which has many variables, including winter temperatures. Some swear that if an engine has been run for years on non-detergent oils, such oils should continue to be used. When I acquired the sedan 19 years ago, I weaned it off the non-detergent oil it was accustomed to by (1) dropping the pan, lines to main bearings, and oil pump screen and cleaning them out, (2) filling with 6 qts non-detergent and 3 qts detergent, (3) running the car 300 miles and changing oil HOT to 6 qts detergent and 3 qts non-detergent, (4) after 500 miles changing to full detergent. There have been no ill effects detectable from this procedure.
In the very early days of detergent oils (1950s), the detergency was much higher and there was THEN indeed a risk that detergent oils could turn loose deposits which could potentially clog oil passages and cause a catastrophic engine failure. That was 60 years ago! Now, most authorities agree that modern detergent oils will not loosen existing deposits.
It comes down to one’s own decision. Please do your own research. The above is what I do, and I’ve never had any ill effects, and I love to DRIVE my Pierce-Arrows!
What I think i was saying in the above is that the first criterion is to use oils with sufficient ZDDP.
Tom’s issue is primarily the suitable “weight” (i.e., viscosity) of oils. I recall Atlanta summer temperatures (actually, Fort Benning’s) all too well, and believe that your garage may drop below freezing during the winters, but not too much. Given those considerations, either 15W-40 or 20W-50 might serve as all-season oils, assuming that Pierce-Arrows are rarely started or driven on your coldest days.
Tom, You may also want to look into the “Classic Car 15W40 Oil” sold by the Indiana Region CCCA and made by the D-A Lubricants Co. of Indianapolis, link attached below. D-A is a manufacturer of diesel truck engine oil and this “Classic Car” oil is rated at 1,600 PPM of ZDDP (zinc and phosphorus).
We’ve used this oil in our high-compression 1956 Packard V-8 beginning about 6 years ago when the ZDDP in modern motor oil started to be reduced (by government regulation), first with SAE/API service code SM and now with even further reduced ZDDP in SAE/API SN oil.
Right now in our 1601, we’ve changed the non-detergent NAPA/Valvoline 30W, SAE/API SB, 5 times in the 1,500 miles that have been put on it since 2010 when it came out of 58 years of storage. Before the car was first started in 2010, the pan was dropped and about 1/4″ of sludge was cleaned-out, the engine had just 31,000 miles at that time. After 5 changes, the oil is now running clean and we will eventually “wean” (as George has described above) this engine over to detergent, high ZDDP “Classic Car” oil, maybe after another 5 or 6 non-detergent oil changes.
Hope this helps, Stu Blair, Cincinnati, Ohio
Last year I started using Rotella 15w-40 in my cars.
Even though it was a very hot summer during the tours at Kalamazoo
and at the Gathering at Gilmore, I didn’t notice any lower oil
pressure than in the years previous with straight 30 and 40wt oils
And, considering the quantity of oil our cars hold, the large size
containers of Rotella available at TSC stores and Walmarts helps with
the chore, reducing the number of oil containers.