Flat tappet/zinc content concern ...

Messages
4
Location
North Carolina
Hi everyone. I've searched prior to posting with no luck, just confused. I have two older GM V8 powered engine cars. 1975 Pontiac GrandVille, 455 1980 Cadillac CDV. 368 I'm lost as to what spec oil I NEED. These cars sit in an unheated garage in NC, mild climate. I used the QS 10w-30 with added zinc levels in the 455 this spring. Is this appropriate? What change intervals would be recommended(I change in the spring yearly now)? Thanks for your time. SL.
 
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8,859
Location
Texas
If those engines have stock cams and lifters, then you really don't have much to worry about. You *could* use the latest SN-rated 5w30 without concern at all. I would pick by grade first, then by additive package. Any of the "high mileage" oils are a good pick. An HD oil (Rotella, etc.) is also a good pick, but don't go overboard with the viscosity. Stick to something pretty close to what's recommended. Most of those older engines would do OK on a 40-grade, so something like T6 5w40 would work. Or if you want to be extra certain, get on Amazon and order something like Royal Purple's "HPS" (high-performance street) series of oils, which are tailored for that type of engine and available in all the right grades. Amsoil, Redline, and the other boutique blenders all offer similar products. You can see by my .sig that I have two vintage big-blocks. I've been running them on M1 0w40 the last couple of years, and I've used Rotella T6 as well. No issues or concerns (other than I'd actually prefer a 30-weight) at all. The thing about modern 40-weights, though, is that they're exempt from the Zn/P limits that the API ratings put on 30-weight and lighter oils.
 
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1,227
Location
Columbus Nebraska
By QS 10w30 with added zinc, do you mean QS Defy ?? If so, from what I have read here and elsewhere that is what I have switched my old (1950-1965-1980) vehicles to now that I have used my stash of SL rated oils.
 

Squashman

Thread starter
Messages
4
Location
North Carolina
Originally Posted By: 440Magnum
If those engines have stock cams and lifters, then you really don't have much to worry about. You *could* use the latest SN-rated 5w30 without concern at all. I would pick by grade first, then by additive package. Any of the "high mileage" oils are a good pick. An HD oil (Rotella, etc.) is also a good pick, but don't go overboard with the viscosity. Stick to something pretty close to what's recommended. Most of those older engines would do OK on a 40-grade, so something like T6 5w40 would work. Or if you want to be extra certain, get on Amazon and order something like Royal Purple's "HPS" (high-performance street) series of oils, which are tailored for that type of engine and available in all the right grades. Amsoil, Redline, and the other boutique blenders all offer similar products. You can see by my .sig that I have two vintage big-blocks. I've been running them on M1 0w40 the last couple of years, and I've used Rotella T6 as well. No issues or concerns (other than I'd actually prefer a 30-weight) at all. The thing about modern 40-weights, though, is that they're exempt from the Zn/P limits that the API ratings put on 30-weight and lighter oils.
Stock all the way around. Thanks for the reply. I've an 11' Challenger R/T 6m. Great cars.
 

Squashman

Thread starter
Messages
4
Location
North Carolina
Originally Posted By: old1
By QS 10w30 with added zinc, do you mean QS Defy ?? If so, from what I have read here and elsewhere that is what I have switched my old (1950-1965-1980) vehicles to now that I have used my stash of SL rated oils.
I'm not sure about the Defy... It come in a 5qt red colored jug.
 
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8,051
Location
Michigan
Is that Quaker State Defy you're talking about? It's a decent oil for the application. Valvoline VR1 10w30 has higher Zinc content than Defy. I've been using it in my '72 GMC for years. Your local NAPA can order you a case of it. Brad Penn is another high-Zinc oil, but is harder to find and is more expensive.
 
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1,066
Location
Minnesota
Squash-I have a similar Pontiac and older Buicks. I don't worry about this issue particularly. One reason is that in checking valve spring pressures doing engine work on such, I've found that the numbers have degraded enough from new so that early valve float is more likely than any cam/lifter problems. Others may differ tho!
 
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10,910
Location
Cincinnati, OH, USA
Given my history with older GM engines eating camshafts, I would use a 10W30 dual rated HDEO such as Rotella T5 10W30, or move up to the QS Defy 10W40-it has more zinc/ZDDP than the 10W30.
 

MolaKule

Staff member
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21,950
Location
Iowegia - USA
I personally have not seen any GM V8 engine with extreme wear on Camshafts. However, I usually change out the camshaft at 150,000+ miles anyway for a longer duration, higher lift camshaft when I do a restoration.
 
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Messages
14,828
Location
Central NY
People always worry about this in the Jeep world with their 4.0s. I've always thought that the Jeep 4.0 doesn't have enough valve spring pressure to wipe a cam lobe, and the last of them (produced 8 years ago) is going to be old enough that the existing cam is already work hardened.
 
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1,821
Location
ventura, ca
I use Rotella 10w-30 in my old cars and have never had any problems at all. I don't think a supplement is needed. There are oils available that do have a healthy dose just for that like from Amsoil.
 
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13,098
Location
Indiana
Originally Posted By: bullwinkle
Given my history with older GM engines eating camshafts, I would use a 10W30 dual rated HDEO such as Rotella T5 10W30, or move up to the QS Defy 10W40-it has more zinc/ZDDP than the 10W30.
Really? I wouldn't have thought this.. o.O
 
Messages
228
Location
NE Oklahoma
Originally Posted By: Squashman
Thanks for the info. Is adding a Zinc supplement beneficial?
I do have some concerns that 800 ppm zinc/phosphorus (zddp) levels in today's oils is nor sufficient for the older flat tappet engines. I don't have much experience with GM. products since I was born into a Ford family and don't want to written out of any wills by driving a Chevy. But I do know that the vintage Covette crowd are of the same mind; the 800 ppm zddp in modern oils is not enough. I use an oil that has more than that, Mobil 1 15w-50 has 1300/1200 zinc/ phosphotus. And Mobil 1 0w-40 in the winter @ 1000/1100. I've been using the 15w-50 oil for about 18 years and over 400,000 cumulative miles in several Shelbys, Mustsngs, and Galaxies. It works great regardless of how hard ,or how babied, the cars are used. Mobil also recommends the Mobil1 15w-50 for all vintage flat tappet engines , all of which came from the manufacturer with a 10w-30 recommendation. If you can't bear to use anything heavier than a 30 wt. then I'd advise buying some cam shield. Is by far the finest zddp additive sold today. http://www.cam-shield.com PS. all the Mobil 1 high milage formulas have the same zddp as the 0w-40 @ 1100/1000. I would consider that a are minimum for the older cars, with 1200-1300 a more "comfortable" number. The cam shield product comes with a formula that informs you exactly how much to use to arrive at a desired zddp level. No other brand of additive does that. They all say, just dump the whole can in.... Not very informative. Z.
 
Messages
28,123
Location
Regina, Saskatchewan, Canada
Originally Posted By: MolaKule
I personally have not seen any GM V8 engine with extreme wear on Camshafts.
I hope you're not talking about small blocks, Mola. wink I wish digital cameras were around in the day. Nonetheless, obviously the "high ZDDP" oils of the day didn't help either, and those were some very high mileage engines. I wouldn't have an issue using a normal PCMO or something like Defy or VR-1, either. The Defy is what I have on top for the old F-150, not like it has high spring pressures, either.
 
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