What needs to be done to the engine, when adding Lucas Oil to a rough running car smooth right out?


Asked by Dec 02, 2011 at 09:16 AM about the 1992 Nissan Sentra

Question type: Maintenance & Repair

Last summer my '92 Sentra really started running rough. Someone suggested adding Lucas Oil to the gas. After a couple of bottles, the engine started running smoothly again. This past week, it started running rough again. What needs to be done to the engine to accomplish what the Lucas Oil did this summer?

11 Answers


Full tune up of your fuel system would be a great place to start. The Lucas oil helped clean deposits out of the system, mainly from the fuel injectors. Don't forget to put a new fuel filter on as well.

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I know it has been several years since its last tune up. Without getting real involved in explanations, would you give me an overview of what exactly you would do if you were to give my '92 Sentra a tune-up. Also what tools you would need. Thank you so much.

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Well, a basic tune up would consist of oil change, air filter check, new spark plugs and plug wires, and a fuel filter. This should be able to be done with standard tools... To get a more in depth look into things, would be such as fuel pressure check, compression check of each cylinder, and to check if a vacuum hose is leaking. These tests, you would need a fuel pressure gauge, and a compression gauge.

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This is something that I have never done, always had friends do it or a mechanic, but always felt like it was someting I should learn. So I'm going for it. Thank you.

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Well, if this is your introduction to "at home auto repair/maintenance" (as i like to call it) I would highly recommend purchasing either a Hayne's or Chilton's repair manual for your specific vehicle, available at most auto parts stores. It will run about $20, but is WELL worth the cost. That is the first thing i buy when i get a different vehicle. I would be lost without it! It will cover everything from basic maintenance procedure's, to complete teardown's and rebuilds. Also do not hesitate to ask questions when picking up stuff at the parts store. Ask if their are any specialty tools you will need, how to use them, and if they would know any little tips or tricks to make the procedure go smoothly without any unexpected surprizes!! BEST OF LUCK TO YOU!!!!!!!!

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Because of weather mostly and the holidays, I finally got to it today(12/28/11). I replaced the spark plugs. Spark plug wires. Distributor cap and rotor, and a new fuel filter. Although it is running a little better, it's still missing something. It just doesn't have that purring sound like I've been used to for years. It's closer, but not quite there. Here's something that I'm sure is significate. Each spark plug had some build up on it, but the number one spark plug was wet to a degree with oil on the tip. I don't think that is a good sign, but how bad of a sign could it be?


There are two things that come to mind when i hear these symptoms... worn piston rings, or bad valve guides/seats. To maybe figure which of these (if either) might cause oil on the plugs, here are a few cause and effect tips that might help narrow it down. We already know oil is starting to get where it is not supposed to be, now we just gotta figure where it is getting in from. Does the vehicle smoke after sitting for a bit (going through a drive-thru for instance) and accelerating, leaving a cloud of smoke? If so, the valve guides might be worn to the extent of leaking oil into the intake manifold at idle, but not at higher r.p.m. (1500 or higher) I have seen this before with the build up on the plugs, but not so bad that it had oil was on the tip. What about loss of power? If it has a decently noticeable loss of power, then the rings might be getting worn out, letting oil seep past slowly into the combustion chamber. This would usually cause almost constant smoking of the vehicle, sometimes very heavily, to not even noticeable. I could see this plausible for the number one plug, but not so much for the others. I am currently driving a truck that has worn valve guides (need to get the head reworked or just get a new one) and it has been like this for almost 2 years now. I also had a vehicle that had worn piston rings, constantly smoked, and had no power at all. Always had gummed up plugs, but got rid of it before i had an accurate idea of how long it would last. It made it almost 1.5 years with worn rings, but still ran. Keep an eye on the oil level since it is getting into the combustion chamber. Either of these fixes is not cheap, (reason to why i didn't fix it, cost more to fix than my specific vehicle was worth) and hopefully this helped out in some way.


After your last post, I went out and checked the oil. It was right at the "full" line. I decided to take it for a short spin around the neighborhood to see if it had lost power. (I have been driving my Pathfinder since the Sentra started acting up) I couldn't believe what happened next. It has never had any smoke before, yet yesterday, as I took off down the street, it looked like I was fogging for mosquitos! I haven't seen a car smoke like that in 20 yrs! I went 5-6 blocks and it seemed to have pretty good power. But by the time I got back to the house, with part of the "haze" still in the air from when I left, the Sentra wasn't smoking at all! So what I did next was to spray the throttle throat with cleaner and replace air filter. It helped smooth the roughness a little more, but still not back to normal. By normal I mean, when I come to a stop, I can't tell if the car died it's so smooth and quiet. Today I started it and just let it run for awhile and besides not "purring", the exhaust smells different than it ever has before. I should mention, that all of this happened on the way to the store and back a couple of weeks ago. I left, car ran fine, by the time I got home, running rough. I'm not trying to overload you with details, just trying to give you as many "clues" as I can. I got a Chilton repair manual, they were out of Haynes for Sentra, and the picture they used for different spark plug problems was way worse with the oil on spark plug than my spark plug was. I know that replacing everything I did sure didn't hurt anything, but this summer, the exact same thing happened, and after I added the secound bottle of Lucus Oil, the engine went from rough to purr right before my eyes. Here's one more thing I'd like to run by you(I am sorry for the book,HA!) Auto Zone told me to set gap on spark plugs at .044, yet in Chilton, it said .041. Should I take plugs out and change the gap?


I wouldn't worry about resetting the gap really, I've never noticed a difference in the gap. To me, it sounds like a head problem. With the engine running, it burns off the oil without being noticed, cause there is so little of it. While the engine sits not running for a while, the oil that has been pumped through the head slowly seeps to the combustion chamber, burning off at first start up and drive. It's different hearing that it started just a couple weeks ago, since a head going bad takes a long while. If it were the rings, it would be an almost constant smoking. Not bad, but enough to notice and say.. That's different... If this happened over the summer, maybe give the Lucas oil another try and see what happens this time?


I guess we have come full circle. I did try Lucas Oil this time, but it didn't work. Thanks for your help.

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