Use of Lucas Oil Treatment: Only at oil change?

I realize some people will say bad for your engine, but I had good luck in reducing oil consumption so will continue to use it.
The company says use at every oil change. Over time as oil is added between changes, the ratio of Lucas to oil will change because no Lucas is added with new oil. (Mixture will become more “dilute.”) So why not add a proportional amount of Lucas with each new oil addition to keep ratio the same? As it is, the effect of the Lucas seems to diminish with time as one would expect, until the next oil change. What is wrong with my logic?

Your logic seems sound to me. You’d just be using a mix ratio…kinda like chainsaw fuel.

Are you burning that much oil between changes? How many miles/quart? I doubt its effectiveness is being affected by the ‘dilution’. And if there’s a lot of dilution, it must not be doing any good! I wouldn’t say it does any harm, but I’d be surprised if it’s doing much good.

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No harm in trying it out. If if it helps, great. If not, you can stop.

Thanks all. Glad my logic makes sense since it didn’t to the guy at Lucas- English not his first language-who couldn’t even understand my question! Let’s see if oil consumption (seemingly much improved by Lucas) remains constant between oil changes.

As a non mechanic or engineer, isn’t this just increasing the weight of the oil? Why not just switch to a heavier oil if allowed?

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Lucas claims the it sticks better to the engine internals than oil does- making for less wear on engine startup where there isn’t oil pressure yet. at least that’s what the cool little display at the parts house says.

I’ve used it to prolong the life of some pretty worn out diesel engines in the past. In what may have been little more than a placebo effect, it helped. It certainly didn’t hurt those engines.

not sure I’d use it nowadays. I quit experimenting when International started using oil pressure to fire the injectors.

You logic seems impeccable. Not commenting on the merits of the product of course, never used it. You could mix up a batch in a container, whatever proportion of oil/Lucas you think best, and when doing a top-up, use that.

Seems like a lot of trouble for very little gain. How many quarts are added between changes?

I have read that this is a great GEAR OIL but not so much of a motor oil. Those displays in the parts stores are a good illustration of that. There are videos on Youtube showing how it foams at high speed and isn’t the best for motor oil. I will not use it and consider it a snake oil product. That being said, if your engine is about toast, it might not be the worst thing to use.

My rule of thumb for an oil burner was to move up to a 5W40 from a 5W30 when I had some of them. This seemed to reduce consumption but in theory shouldn’t hurt at cold starts, etc. I have also used 0W40 with no issues. Going from 5W20 to 20W50 in a modern engine likely isn’t a good idea. Going up a tad shouldn’t hurt anything, especially in an engine that is worn out of clearance. Remember that oil pressure is important for valve lifters and cam timing in modern engines so don’t go too crazy with a thick oil.


Is the cost of the additional Lucas less than the cost of the additional oil you would have to add if you didn’t add Lucas between oil changes? I’ll bet not.

Before I would use an additive which effects the oil viscosity, I would use an additive which directly reduces the oil consumption.



This is a good discussion about why Lucas is best left out of your engine.

Thank you all for your interest. My logic has been confirmed.
One guy I went to said never to use Lucas, but my regular trusted mechanic does. The opinions seem to be about equal, pro versus con. What’s a body to do? I do understand the arguments against but I guess I’ll have to take the chance that there’ll be trouble down the road because it has been so useful in reducing all consumption. One person mentioned that Lucas has an additive which is supposed to make it more effective than thicker oil. Since I have tried thicker oil and it did nothing, guess I’ll have to believe Lucas’ claims.
Great response! Thanks again!

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Just how much oil consumption are we talking about?

How many miles before you need to add a quart?

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I am one of those anti Lucas and anti additive guys. I believe the best thing is to fix the car. But that being said, if the car is not worth fixing right then I’d put all kinds of additives in. But these are last ditch efforts and I should be saving for another vehicle.

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Lucus display, but with a power drill:

About 700 miles

I have about 165,000 miles. By your standards, would that qualify for adding “anything?”

Instead of Lucas have you tried Restore?