Reader Question: Seafoam vs. Lucas?

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

Dave asks: In my area at least, Seafoam is the gasoline additive to use. But I just noticed a half empty container of Lucas upper cylinder lubricant on my bench. Cheaper to use than Seafoam. I wonder if you have an opinion??

I have all old vehicles with old engines. which all sit quietly for extended periods, periodically. Did not realize the possible damage till I read this article.

My reply: I have used Lucas in the past and have always been happy with their products, especially their gear lube. I recently used it to refill the gearbox in an old Toyota truck – my neighbor lady’s truck – and the transmission went from being difficult to shift when cold or hot to easy to shift all the time.

I have no personal experience with Seafoam but have never heard anything bad about it. The Seafoam gas additive has a fuel stabilizer as well as upper cylinder lubricant. That ought to be a good deal for older (carbureted) vehicles especially.

I think using either won’t cause any problems based on that and based on the fact that both have been around for decades – which is usually a good sign.

I will try to contact them (Seafoam) and see whether I can get some samples to try and if they do send ’em, I’ll do that – and report!

. . .

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  1. I don’t have any opinion on either for automotive applications, but when it comes to small engines, Seafoam is absolutely the stuff to use as a fuel additive.

    2-stroke, 4-stroke, brand new or antique, I don’t let ethanol-contaminated fuel near any of my small engines (chainsaws, lawnmowers, garden tractors, log splitters, snowblowers, whatever). But sometimes they come to me already harmed by the Iowa Tax.

    Seafoam and ethanol-free premium gasoline does the trick. If something runs poorly, a couple of tanks full will normally settle it down. At the end of the season, I don’t have to worry about draining every drop. If it has ethanol-free gas and Seafoam, I know it will start right up months later.

  2. Eric,

    When I had my Kawasaki W650, one of the carbs was messed up-thanks to the alcohol laced gasoline! One of the jets was corroded, so only one of the two cylinders was working. A biker buddy told me to run some Seafoam through it. I did, and the problem cleared up on its own. I would use Seafoam again! It’s good stuff… 🙂

  3. My understanding is that as an oil additive Seafoam is a cleaner/detergent and Lucas is a lubricant.

    I’m trying to solve an intermittent noisy lifter problem and I had both recommended: SF to clean out oil passages and Lucas replacing a quart on the next oil change.

    Also I read about using Rotella 5w40 in older gas engines. I’m confused as to what to do. I hate to spend $1000+ to pull the head on an otherwise great running engine.

    • Anon, a lot depends on the age and condition of the engine. You’ve got it right- Seafoam is a detergent; Lucas is a lube/viscosity modifier.

      On an old/worn engine, a detergent can dislodge things and make them relocate to places where they could do harm, or can clean out stuff that is actually helping to seal things that need to be sealed, or which are acting to keep clearances in spec and which if removed will make things worse. And viscosity enhancers can reduce oil flow to vital things….

      This is why I generally do not use additives, unless it’s a last resort on something to try and “save it” if there is a problem that is otherwise not worth fixing. It’s like: If nothing’s wrong, you don’t need an additive, except perhaps something like Techron occasionally in a tank of fuel to clean up injectors and keep them healthy.

      What you describe though, for the lifters, can help. You can do as you say, but just run the Lucas briefly, and then change the oil, and use what you normally use with nothing added. Or, you could first just try adding a little Marvel Msytery erl to your oil….that stuff does wonders for lifters- Run it for a few hundred miles, then change back to clean oil.

      With modern engines- pretty much ’03 and newer, I’d just avoid adding any additives to the crankcase….unless it’s a last resort, as they can do a lot of damage to newer engines, which have very tolerances- and the ones that say they’re safe for newer engines, will not “fix” anything.

      • Not exactly modern, 1988 4.0 straight six though they did still make them up into the new millennia. Not sure the SF dosage, I just put in the directions 1 oz per qt and it didn’t say anything about limited time/miles. I can’t really see any change yet. It just comes and goes more or less randomly. It will be clacking like crazy and then just stop. Seems to go away with more rpm so driving is ok.

        • Oooo! Those are great bulletproof engines! Clacking though- as opposed to ticking? If so, sounds like the valvetrain may just be very worn- Seafoam ain’t gonna help that.

          When’s the last time the valves were adjusted? A lot of people don’t keep up on that…and when it gets bad, it’ll make noise.

          I wouldn’t put any detergent additive in the crankcase of anything that old (Gas tank: O-K)…but some Lucas…the kind ya leave in, won’t hurt that engine. But if you haven’t been up on the valve adjustments, check it and correct if necessary- it’s easy, and’ll make a lot of difference in both performance and durability…and quietness…if it’s really out-of-spec!

          • There is no adjustment. The noise just comes and goes seemingly randomly. Like just now, it was clacking at the gate and then a hundred yards up the hill at the garage it was quiet again.

            • There’s no valve lash adjustment on an ’88 4.0??? Methinks you are mistaken. The noise should pretty much be consistent though…

              Is there asny consistency to the conditions under which it makes the noise? e.g. facing uphill or downhill vs. level ground; only when not under load, etc.?

              This is not sounding like lifters; possibly still could be lash adjustment, if it’s really bad.

              Sure it’s not developing a rod knock or ring slap…or is even in the motor and not on an accessory(belt, alternator, etc.). Can you use a long screwdriver like a stethoscope and try and isolate exactly where the noise is coming from? (Be careful!)

              • Nunz, as far as I know there is no valve lash adjustment on these since hydraulic lifters are used. It might be worth checking that the rockers are properly torqued down. Might have loosened up over the years.

                This video shows the 4.0 valvetrain on a noisy engine in pretty good detail, though unfortunately the source of the noise was not located:


                (If you watch and listen carefully in the video above the clattering appears to be in time with the valve operation. I’d say it was bad lifters.)

                • Hi Jason,

                  I’d lean toward lifters also. And it might just be a sticky one. Which is why the first thing I’d do is the easiest thing – change out the oil with Amsoil and drive it for a bit and see. Amsoil does a very good job of cleaning the insides of an engine without the risk of running solvent through the engine.

              • Another possibility to check for would be a bent pushrod or pushrods. Easy way to check those is to pull them and roll across a good flat surface, like plate glass. (If pulling out pushrods to check be sure to put them back in the same place since the parts wear into each other.)

        • The 4.0 is a great engine but even by 1988 standards was not all that modern. It’s basically an updated Rambler six with a design dating to 1964.

          From your description it sounds like sticking or worn valve lifters. Back in the day we frequently used Rislone to free ’em up if the problem was gum and varnish rather than wear.

          • Hi Jason,

            Another option – in the case of varnish – is to change the oil with Amsoil. If Eight were around, he’d probably amen this. Amsoil does a great job of cleaning an engine that’s internally dirty, without the risk of using a solvent.

            • Eric, is Amsoil synthetic? I’ve always heard that it is good stuff….but one does NOT want to start using synthetic oil in an old engine if it has been living on regular erl- as it’ll almost always result in making it leak….and going back to regular oil will not stop the leaking…….

              One has to be very careful about upsetting the “status quo” in older engines.

              • Hi Swamp and everyone else asking about 8,

                I spoke to him recently and he’s fine. His computer’s toast and he hasn’t got a new one yet.


                    • Heh, Jeremy, I thought for sure that 8 got hut-hut-hutted or something- what with no posts here, no reply to email….

                      That’s why I keep an old laptop, even though I don’t like laptops- in case my ‘puter croaks. How would one even shop for a new ‘puter without a way to git online?! (Old $90 used Thinkpad off Ebay years ago…and it still works great!)

  4. Seafoam and Lucas both make some excellent products. I’ve used Lucas’s respective products in automatic and manual trannies with great results; I’ve flushed engines with Seafoam (Through the intake, via the brake booster vacuum hose)….but one has to be careful, as I believe doing so can harm/clog catalytic converters- but for a gas additive, the only thing I really vouch for is Chevron’s Techron stuff…as it’s one of the few that contains the additive that actually works to clean the fuel system- especially important for fuel injectors and throttle bodies- anything old enough that it doesn’t have TBI or injectors, I don’t think fuel additives actually do anything- though many old mechanics I know swear by adding a little Marvel Mystery erl to a tank of gas to lube things up in older vehicles- but personally, I’ve never felt the need to add anything to pre-fuel injected vehicles.


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