woodcrest

What are the ideal plugs to use in my 89 C4? Finishing up a head gasket job, the car had a mixture of Autolite 3936 and BETU platin 828. THe car has 110,000 miles. Thanks

vader86

Delco Rapidfires #5 are all it needs, just gap it correctly.

84 4+3

Whatever delco is reccomended. I think I run r45ts or something like that. In a bone stock setup, that's the plug designed for the thing. My truck throws a check engine light if I don't use delcos lol.

mazdaverx7

I use NGK spark plugs in my Corvette. I have used them in all of my Corvettes over the years and they have always been excellent plugs in the Corvette and they hold up extremely well.

woodcrest

OK, which NGK number?

aklim

https://www.autozone.com/ignition-tu...24183_0_0_1212

This is for Aluminum heads so those will work nicely. No need for the fancy ones if you are stock.

mazdaverx7

Without going out to look, I believe the ones that aklim posted are the ones I used when I replaced the spark plugs in my aluminum head 86. They have been fantastic thus far.

BlowerWorks

The ideal plug heats up rapidly and stays clean w/o fouling. Also the plug cannot get too hot and cause detonation. The NGK irridiums are a great choice in my humble opinion !

aklim

Isn't that true if the correct plug in the correct range is inserted?

I would think that on an annual basis, I can change the cheaper plugs and monitor the status more precisely instead of buying more expensive and leaving it longer. Less chance of a corrosion caused seized plug.

vader86

Plugs should be changed out at least every 2-3 years, I'll never trust a plug that they say should stay in 100,000 miles.

My modded engine uses a plain Autolite 3926

aklim

If you are selling a higher end car, sure. For most of the cheaper domestic stuff, the less maintenance you can tell the moron it needs, true or not, it will help sales.

BlowerWorks

No !

Tom400CFI

We just sold our '05 CTS-V. It had 167k miles, still had the original plugs in it. They work.

aklim

They will work but would it be as efficient? At 80k,i had a Ford Ranger that worked. Plug gap was larger than spec. MPG might be higher, IIRC after the plugs were done.

Tom400CFI

MPG, performance, idle quality....etc, etc...all remainend perceptibly unchanged. And that was going 67% beyond the recommended change interval.

I wish the T56 lasted as long as the spark plugs did.

84 4+3

My stockers were 10 years old and had 100k on them when I replaced them on my truck. No problems there. I just replaced them again this spring or... 5 years and another 100k. I could have put them right back in. They looked better than some new lower end plugs you can buy at the store. Gap was perfect and the plug was nice and clean.

There is a hell of a lot of testing done to make sure even an idiot can't kill the freaking thing using the recommended intervals by any manufacturer. Some say more expensive brands recommend shorter intervals because of the quality that goes into it. In my world when they recommend changing something in a shorter interval than what the supplier of that part states, it usually means someone cut a corner somewhere/didn't do something right/wants to save a buck and used a cheaper part that can't survive the interval... The stories I could tell from work, but I would lose both my current job and my job prospect if I said anything more so with that... that is all. All depends what side of the desk you're on.
Bah, you want to blame anyone for that crap it's BMW. Who there in their right mind thought a transmission was a lifetime fill I will never know... And it went down hill from there. You need a Phd in engineering just to find a freaking dip stick in some cars.

aklim

That's different in my case. I think I picked up 1 or 2 (under 2 for sure, more than 1) when I changed the plugs which had larger gaps than stock with the tip worn out. No change in anything other than mpg. I fill a tank up, drive till it is at empty and a bit more before I fill up. Yes, I know, my pump will die if I do run dry, right?

aklim

I think that is the issue right there. IF, and the operative word is "IF" the plug gaps are good and not fouled, it can go on for a long time. Unfortunately, without R&R, it is impossible to know if the gap is good or not.

I think you forgot to add "until the warranty is up".

Are you sure? MB also did that although they did backpedal on it later on. I know that is true for the MB 722.6 trans. All of my 3 722.6 transmissions did not have a dipstick. You have to break the tab to take the fill cap off. The way to check the level is to get it to temp and check level with the dipstick the shop has after it has been cleared by SD Connect to be at the right temp. There are a lot of people that just drive it for a few miles and assume it is right and check. I am more **** and insist the shop checks it with the appropriate dipstick and using SD Connect.

84 4+3

I think BMW did it first. Those Germans do some strange things though.

The biggest problem with modern style plugs is if it starts plating the electrode to the ground strap. I've seen it happen. Don't know what causes it but I would guess spirited driving. (Never had it happen on any of my vehicles that I maintain, seen it on one fleet vehicle for the company though. and that was a dodge so there were more than likely other issues contributing to that. ) Most companies spend hundreds of thousands of dollars paying for R&D of their intervals. When GM told me to run the oil in my truck out 14-15K miles I was a little skeptical. Used oil analysis says it could go 20+ easily. Since I'm putting 40k+ a year on the thing that saves me a lot. Doing 3k intervals would mean oil changes like once every 6 weeks. If it blows it blows. Truck owes me nothing at this point but the data says its fine.

On our cars, the vette, every couple of years is a good idea. Sitting for long intervals with the tips corroding probably isn't good for them and removal. And besides, most owners see cars as disposable anyway. Who cares what happens at 100k, I'll be in the next lease is the mentality of most people I know. I happen to be in the run it till it dies crowd and so far so good. Watch, now it'll blow up tomorrow going to work. What people do for maintenance can't be proven or disproven to extend the life of the vehicle anyway. Too many variables. It's just like break-in. Everyone has their method and who knows what's best.

I guess what I am saying is that if something blanketly says "don't worry about this." you probably should worry about it. Lifetime anything, for example, is something that probably isn't lifetime. Accept but verify. If for example, you hear of the plugs snapping off in heads using the recommended interval, then maybe you should do it sooner. I'm reasonable. If it's a problem I'm not gonna go by the manual is the bible. Again... people eff up at my job all the time. But sometimes a 1 million dollar renovation turns into suing the company for 4 mil because they botched the fume management system and force a shutdown and thus loss of contracts. **** happens. People over look things. I'm reasonable.

aklim

I don't understand it either. I guess maybe I see it more here where people try to stretch out the fluids until something goes sideways. MB at least does recommend 2 year brake flushes and 3 year coolant and backed down from the lifetime fill so it seems more hopeful over there? Or maybe the grass is greener?

And Ford told me to change their Motorcraft oil every 3K on the Powerstroke. Dump 15 quarts every 3k. Switched to Rotella T6 5W40 and Blackstone Labs said every 6500 but I change at 6000 for simplicity sake.

I became more **** about the plugs after I had to remove a head TWICE because of stuck glow plugs that broke. Changed the schedule to an annual R&R and it solved that problem. As to the mentality, well, that is true. I honestly don't know how mechanics keep a straight face when their customers come with these issues. You are right that it has some likelihood of being the next guy's problem. However, when the music stops and you don't have a chair to sit on, well.....

To me, factory recommendations is the LOWEST POSSIBLE STANDARD that I will accept. It's part of a sales pitch to draw in people. Remember, the factory spent money to determine the interval is so they minimize the warranty cost but sell the most they can. If they say "You must do "X, Y and Z" on an annual basis and another company says "Only X" every other year, that will play a role when the moron, aka buyer, makes a decision.