Reader Question: Oil Additives?

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Here’s the latest reader question, along with my reply! 

Tammy asks: What do you think about oil additives that claim they will reduce wear and tear, improve mileage and power? Are these claims bogus?

My reply: These claims may – or may not – be valid. The problem – at least potentially – is that modern engines, especially those with variable cam/valve timing systems that use the oiling system to do their thing, can be very sensitive to oil viscosity and other such parameters. Unless the manufacturer of your vehicle specifically – in writing – okays whatever the additive in question is, I would recommend against using it, particularly if the vehicle’s engine is still under warranty. If a problem does arise and it is determined it arose because an additive not recommended by the car’s manufacturer was used, the damage will almost certainly be paid for by guess who… .

My “50” on this is that your best bet is to use the exact grade (and viscosity) oil recommended by the car’s manufacturer – and to not use off-brand/no-name-brand Mystery Oil or additives to make up for the sketchy quality of the cheap oil.

As an aside: Some older car engines do need a specific additive – it’s an anti-wear additive that used to be in most oil but has been largely removed from most store-bought oil. It is generally marketed as “ZDDP.” But you’ll only need to worry about this if you buy a car made before what are called flat tappet camshafts stopped being used in cars, which was about 35 years ago.

If you do have – or buy – a car made before the early 1980s, then you will want to add the ZDDP, or use a specialty oil such as Amsoil ZRod (which I use in my ’76 Trans-Am) that still has the necessary good stuff.

. . .

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11 COMMENTS

  1. Do the “crate” small block Chevy engines that you can buy for older pickups have the flat tappet or modern cams?

    • dread, you can get them any way you want. To be specific, the first of the old TBI 350’s were flat tappet and I’ve personally known 3 of them to pass a half millions miles and be doing well. When the moniker was changed from 350 to 5.7L, the camshaft type was also changed. I don’t know of any of those pickups that made half a million although there could be some.

      I don’t know any of the 5.7L that got the good fuel mileage of the old style engine either. Roller cams and all, they were pumped up for more hp, remember, gotta keep and, no, gotta outdo the others EVERY year. Every time I hear about keeping up with the “competition” I’m reminded of the line in ‘O Brother, Where Art Thou? when the radio station owner is told by a colleague they have to keep up with the competition. Of course getting more hp Could be a good thing for fuel mileage and it sometimes is but look at the mileage of new cars that are uber-powerful and literally have 2 fuel injection systems. Some of them get close to the 28 mpg my wife’s 95 Cutlass got day in and out.

      Here’s the living proof of using the wrong oil in an engine. The company I worked for a few years ago had two 5.3 Chevy pickups. They got really good mileage and were seemingly bulletproof. One day one of the operators and the mechanic were changing oil in everything in the yard. Rotella T 15W 40 was the oil of the day and for everything else, it was fine(if you like oil that when you get to the bottom of the gallon jug you see some sort of crap on the bottom, obviously a problem with their system and lack of filtration). I asked the operator if they had any 5W 30 for those Chevy’s. Nope, he said, we only have Rotella T so that’s what we’re going to use. I tried to get him to leave them alone and let me take care of them after I got the requisite oil. Long story short, they somehow only changed oil on one of them, thankfully. The next time I saw that crewcab that got 15W 40 the entire upper end sounded like hell.

      It’s a shame they don’t still make Amalie with no detergent. Then they could save a huge amount of money on oil changes and then take the vehicles to Richie Bros. Auction with some sawdust in the engine to make it seem quiet.

      • So my 1989 350/5.7 is the “flat tappet” ? It runs great at ~206K but I think it had some work done before I got it. I just hope the ex of the lady that I bought it from didn’t screw it up too badly. Apparently he couldn’t be bothered to put in both motor mount bolts which I discovered some time after I got it!

        I also have a 1991 Squarebody Suburban 350 TBI with ~226K that as far as I know is original except that I had to have a head gasket replaced that blew out between 3/5. It’s funny how the newer model year truck is actually the older of the two by generation. I’ve always assumed that the engines were basically the same.

        When those outfits were new, I was still driving 1960s and 1970s stuff and thinking that I was doing pretty good – LOL So I wasn’t really keeping up on exactly what was coming out new at that time.

        I’ve always used Havoline or Valvoline: 10-40 back in the old days, then 10-30, and now it seems that 5-30 is all that you can get. I run up to about 3K miles on the trucks and farther on the 2006 car which has an oil mileage monitor.

        • The 5.7 and the 350 are different engines…inside. The 350 is a flat tappet engine but the 5.7 is a roller rocker. The advantage of the roller rocker is ability to open the valves further and for a longer or shorter period of time without wearing out the cam.

          For reasons unknown to me, it seems the lower hp 350 was the much better engine for the long haul. If you want to use some different oil than what you are using, there are plenty brands that have 5W30, 10W 30. I use Amsoil in everything. It has a pour point lower than any oil I know of and is resistant to heat. What this means is you won’t see as high oil pressure upon very cold start-up as opposed to conventional oil. It won’t break down from heat nearly as easy either so your “hot” oil pressure won’t drop like conventional oil.

          The square body had it’s advantages to what came later although I don’t think the cargo area was significantly different to the newer style. It is probably a small amount narrower at the rear doors or endgate. I prefer the newer style because of changes in suspension, handling, braking, etc. plus I think that early 90’s pickup styling is the best ever made. It’s slicker and just nicer to look at but I have no problem with the square body either and have had a few of those pickups. Sure wished they’d have made X cabs on them. It’s hard to find the crew cabs in that style now.

        • Okay – now I need to go out and look at the build sticker or whatever I have to see if these were 5.7 or 350.

          My 1989 is about six inches narrower inside the bed than the 1976. I have an old seed drill box cut in half for a chainsaw box, that would fit crossways behind the cab in the 76, but I had to mount it lengthwise in the 89. Also somebody gave me a pretty nice old steel cross-over box which fits the 76 but won’t drop down between the bed rails on the 89.

          It’s sort of a trade-off between GMT400 and the Squarebody: the IFS definitely makes for a better highway truck, but solid axle trucks turn much tighter so they are better in the woods. And the 76 with the bench seat is much easier to jump in and out of a few dozen times a day, which is what I end up doing just working around the property and cutting firewood. I swear that the door on the 89 weighs 500 pounds and it’s a killer to push open when you’re on the high side of a side hill. OTOH, the 89 being a bit narrower can fit between trees just a little bit easier.

          Currently what I own is all backwards – damnit! I wish I had a good old K-20 four speed for “ranch” work and wood cutting, and a really nice K2500 with a topper or cowboy camper for road trips.

          Surprisingly I got around just fine with 2wd down in Colorado. I could always use tire chains in the snow but up here the roads can turn to gumbo with a little bit of rain. Chains in mud are no fun at all plus I’m getting a bit old to be putting them on and taking them off all the time like I used to. Now I’m not sure I will ever get the C-20 running again but I sure look at it longingly sitting out there in the yard …

          • Having limited slip front and rear can’t be beat. My neighbor bought a new Ford 4X4 powerstroke. It has an electric rear locker, a neat thing since lockers are a drag during normal turning and simple driving. I don’t know if the front locks or not. it would seem to be a no-brainer to have both lock when you flipped the switch.

            Those old K20 Blazers would climb a tree with the factory LSD’s front and rear. The problem being, you had to order it on one unless it was a “full-time” and that sucked in its own right.

          • Never was a K-20 Blazer; they were K-5.

            I wouldn’t want a locking front on an IFS. Everything up there looks too flimsy compared to the old solid axles. I have new CV axles ready to put in my pickup; just need to get brave and start jacking it up.

            Mostly get around fine with just 4×4 and open diffs. 90% is just not having two wheels dragging. In fact our jeep does the best even in “Full Time” with center open diff in both snow and mud. The axles/suspension follows the varying road camber and keeps weight on all four tires (up to a point of course – assuming there was a road under you to begin with). I never thought full time 4wd was a good idea until I got this jeep and now I love it: just set it and forget it 99% of the time.

            But yeah, the GM full time (NP203) was pretty clunky although I never drove them outside of the dealership where I worked for a while. At the time I thought it was the dumbest thing possible, and even joked that I could convert my pickup to “full time” by just locking in the hubs (so that I could put it in 4-Hi without getting out).

            • My one ton wasn’t flimsy in the slightest. That is a beast of a differential in the front and the 11.5″ diff in the back is the ultimate rear diff. I don’t mess with 3/4T stuff or 1/2 ton. It just isn’t worth it and brakes that last over 200K are just another reason. I pulled(single tire one ton)3/4 T with overloaded trailers out of pure much with my one ton. It was simply another step above everything else….and they still are.

              I have no use for a pickup that will beat me…and itself, going down the road and one that won’t handle handily. With Edelbrock IAS Performer Shocks on that beast, it drove like a Caddy and instantly went into ‘Vette mode when you turned hard. That shock system was even faster to respond than electronic shocks.

              Too bad Edlelbrock shocks are gone now, sold to some lesser entity. I took that pickup up roads meant only for mining haul trucks. It drug the rear diff up the center(high point)and never looked back. The frame was over 10″ in depth and heavy as hell. Yeah, they weren’t thinking the ultimate machine to help overall mileage back then….thankfully.

              I had an argument with my cousin, a guy with a mechanic shop about 14 bolt rear ends. He said the one he had for a 3/4 T was a 14 bolt, just like mine. I learned him up a bit and showed him the difference in the cases and the gears. The 10.5″ ring gear is a decent diff but the 11.5″ is a hoss. The front diff is different too. I’ve dragged everything from 4WD one ton pickups to tractors to big rigs out of the sand. It’s the very reason my frame is connected with a piece of drill collar in the back and another piece of drill collar for a bumper. Go ahead, run into something with the edge of the bumper. Whatever you hit won’t look good but the bumper…and the frame will be fine.

              When I totaled it running into a couple more pickups(Gm’s wonderful ABS not only didn’t work, it didn’t let the brakes work at all), hence me running over 2 other pickups when all that was required to not do so was just a general application of brakes. I was pissed. I should have sued shit out of GM over that one. The dealership with a frame straightener said it was one of a few pickup that would have survived that impact with the frame. The Chevy I hit from behind was 10 years newer, an ’03 I think. It lost its lights and everything else in the front end while mine had very little damage. I saw his bed turn into a hot tub in an instant. And to think that old square body stuff was so much stronger sheet metal wise than what I was driving.

              When getting my pickup fixed there was a one ton crew cab 4WD King ranch pickup with the entire passenger side wiped out, from the front fender to the rear bumper…from a deer hit. They just don’t make em like they used to.

              • Mine is a K1500. It was available at the time and very cheap. I’m just trying to keep it together for now. I’ve already decided that I’m looking for a K2500 next time – a nice enough one that it’s worth fixing everything that it needs. For one thing, the five speed (NV3500?) in mine is a piece of junk. It works and shifts just fine but is too high geared in 1st and reverse. And I’ve heard that they’re not up to even pulling a trailer.

                Trouble is that there are only so many “survivors” out there and probably fewer one tons than anything. Most everything in Montana is beat to hell so I’m hoping to still find one down in Colorado “when I have the money.” I see nice older pickups sitting around in yards down there not being driven much.

                I’d still like to have an old beater squarebody 4×4 for a wood truck. OTOH, I’m planning to just buy a semi-load of pulp wood this year and have it dumped in the sagebrush. So most anything could haul cut-up wood 1/4 mile to the house, even a 2wd, or a trailer which of course is absolutely worthless in the timber.

                • Anonymous, you need a NVG 4500. It’s a HD 3 speed with under drive and Overdrive. It won’t take a Duramax but it stands up to a Turbo Diesel and has that down in the weeds low and a good OD. But with a decent rear gear they get great fuel mileage.

                • Yeah, I know – but I’m not going to try to swap it. You have to move the x-member and TC back and then adjust the driveshafts. Just not worth it for that p/u, at least not now. Have to replace the CV axles because they make so much noise in 4wd.

                  Sigh … pretty much everything I have either needs some serious work or replacement.

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