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1999 Buick LeSabre - Engine questions

I have purchased probably one of the best engines ever made, GM 3.8 V6 3800 Series II (L36) Code K. It came with a 99 Buick LeSabre Custom attached to it and at 122K it is in pretty good condition. It has the usual issues that came with subsequent models, bad horn clips in the steering wheel which is why the 15 amp fuse is pulled, some window buttons aren’t working, the fuel gauge goes all over the place after you fill it up then ends up staying at forever full until you get to 1/8th then it goes to empty and notoriously bad with coil packs causing, I hope, the P0303 cylinder misfire. I have a barely noticeable rough idle when at a stop, no noticeable power loss when accelerating, but I don’t know how it ran without this code and it lurches under 10 mph when coming to a stop.

I did notice a decent crack up the side of the 6/3 pack and I figured out the firing order and traced the wires to the correct cylinders from the coil packs because they were mislabeled due to being bought off different junkyards. I am waiting to have shipped to me a new set of spark plugs, wires and 3 coil packs, (no ICM until next month, on a budget) all GM OEM because I hear that the aftermarket coil packs top out at around 15/16 ?ohms or amps? when the original should be topping out around 10? I haven’t done the engine running pulling the cables off each pack to check for spark yet, been sick, and it seems unnecessary since I’m replacing them anyway. So hopefully it’s that and not something like a piston ring…WAIT I can just swap coil packs to another set of cylinders and see if the code changes to another cylinder!! Okay.

I do have another question. On cold starts I hear a quick ticking sound from the engine that goes away after 20 seconds and doesn’t return while running or accelerating. Specs say to use 10W30 and I checked the oil which is within the top of the crosshatch and the filler cap doesn’t have any foamy oil on the bottom of the extension piece into the top of the engine. I’m curious if this is a normal aging symptom that can be cured by turning up the radio and forgotten or is this a serious problem?

Also, should I stay away from using these once…Seafoam in the fuel tank and Lucas Oil treatment or Royal Purple in the crankcase? I’ve heard that on older engines using these can hurt more than help by removing carbon that was plugging leaks in the manifolds or elsewhere.

Thank you. I know it’s a lot and any advice would be greatly appreciated. I’m 44 and a novice but I have been able to change calipers, rotors, transaxle, oil changes and filters.

Your replacing all the plugs, wires and coils, so hopefully that will take care of the missfire. You might as well do a compression test while the plugs are out. Don’t forget to blow dirt away from plugs before removing them.
As far as the ticking: there’s may be some time before the oil is getting to the lifters. I’m usually against additives, but on this old of a car, I would be tempted to put some sort of oil additive to try and clean some of the passages on my next oil/filter change, then change oil/filter again at 2 or 3 thousand miles.

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Had a similar problem with an old Acura GL. Started to add Lucas oil treatment with each oil change and never heard the ticking noise again, even at cold startup.

Back in the day there was a campaign (meaning a miles and time limited additional warranty) on the 3.8 for plug wire issues. That campaign has long passed so you’re out of luck there.

I would hold off on parts spending until you get the new plugs and wires installed and go from there. Running a compression check with the plugs out is a good idea also.

I don’t think additives are needed except in very limited circumstances.

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Please don’t take this the wrong way

This car doesn’t deserve Royal Purple

You bought a boring family sedan, not a high-powered sports car for track use

Just use 10w30 . . . if you’re a type to lose sleep at night, go full synthetic. Store brand is fine

This may very well be caused by deposits on the “float” part of the fuel sending unit. I had a similar problem some years back, and filling up with top tier fuel INSTANTLY solved the problem

you talking about the horn contacts . . . once you have the airbag removed, those are usually pretty easy to replace, on your typical vehicle

I think you’re on the right track with the full ignition tune-up using oem parts. However, as already mentioned, you might want to do a compression test. In all likelihood, the engine is solid, but you’ll want to know sooner rather than later.

Have you already cleaned the throttle body?

What happens if you turn off the ac at idle?

any change?

I’m pretty sure this car has an iac valve . . . just something to think about

Again, I think you’re wasting your money. You don’t need it

If you’re a Costco member, just start filling up there. The price is hard to beat, anyways

may as well start buying your engine oil there, too . . . that is, if they still stock 10w30. Again, no offense intended, but that particular viscosity is starting to become less popular as older vehicles are wrecked, junked, or simply traded in, to be replaced by newer and more fuel efficient ones

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My 05 Lesabre 3.8 uses 5w30. I wonder when GM moved from 10w30 to 5w30? I doubt the engines are any different internally. I wonder if 5w30 might help the cold start noise?

Telling somebody to go to to a LOWER engine viscosity than specified isn’t something I would advise

Personally, I would advise them to keep using the fluid(s) specifically named in the owner manual

I didn’t necessarily advise it either. More of a question. Although I can’t really see using one or the other to cause a huge issue since they both act as 30 weight when warm.