plugs an' oil recommendations

Ok..got everything to do my HEI conversion this weekend. While I'm at it I'm going to install new plugs and change oil and filter. this is a 75 258 six cylinder w/40,000 original miles. Questions....

I did a search using spark plugs and found lots of gap information, but not a whole lot on brand/heat ranges. I've heard AC's are the preferred brand in Jeeps but looking for opinions and part nos....particularly heat range preferences.

Also, don't want to open up a can of worms, but; Is it a bad idea to run synthetic oil in a jeep that's thirty years old. I know you get superior lubrication with synthetic, but I've read in some instances, it causes seals and gaskets to leak. Anybody running synthetic in an older Jeep ?

Thanks..........also any other tips on a plug change other than using anti-sieze on the threads ?

 

I'm fond of 30wt, Chevron Delo 400
but I'm in So Cal
if your in a colder climate, 10-30 might work for you
I like Champion plugs, which is what Jeep installed from the factory.
I don't care for synthetic products, too pricey for me for a Jeep I drive no more than 3K to 5K miles a year
YMMV

 

I have almost exclusively used Castrol in my vehicles for 20 odd years. I run 20-50 in my '74 232, but it has many more miles than your mill & I believe in heavier lubes. I don't see any reason to run synthetic oil unless you just plain want to. You can change your Jeep oil, then use the synthetic in your lawn mowers, chainsaws, etc.

Champion is good, but more importantly is where you buy your plugs. I would stay away from K-Mapart or Wally World. Nothing is worse than blowing a spark plug or having it break on you late Sunday Nite. Use an established auto parts store like NAPA, etc.
I liked NGK Coppers in my different Hog applications, but cannot justify the extra costs for Jeep.
I think Splitfires are solely Hollywood and you would be better off indexing your plugs.

If you're not familiar with indexing, it involves buying different thickness crush washers from a speed shop, then setting each plug so that the gap faces your intake valve. It does make a difference.

You shouldn't have to worry about heat ranges unless you're at an extreme altitude or micro-tuning fuel/air ratios. It's a good learning experience to try slightly different heat ranges (one step up or down).

I just use a drop of engine oil on my plug threads.

gj

 

Auto Lite is my 2nd choice, nothing wrong with 'em Patrick

 

I go with Champion/AutoLite whichever is on sale and the least expensive 5-30 oil that comes with a starburst on the label.

 

If you're still looking for a heat range, look for the first year HEI/258 set-up in a repair manual & see what plug they used. I don't know much about Jeep V-8's or electronics, but I think '75 was about the first year for electronic, so start there & see how she runs, read/sniff your exhaust, read your plugs, and you'll be able to adjust heat range from there. The first year 6 cyl. electronic may have had more emissions garbage, so keep that in mind. Here's a Chilton's Tune-Up Spec that says a 1975 232/258 electronic used N-12Y @ 0.035" gap.

gj

 

Personally I like Bosch supers.. they are cheap but have a copper core and have served me very well. As for the oil, I use only 10W-30 Mobil 1 in everything including my lawnmower. The cost is easily offset by extending the interval. Yup I even ran it in my dauntless.. no problem.. they used to cause seal problems but the additives package was changes a few years back to fix that..


BUBBA

 

You definitely get a few more Zots from Coppers. I hit North Tejas on a road trip w/Coppers many moons ago and filled up my bike w/ Roadrunner 15% ethanol.
A plug check at the end revealed a pleasing copper-greenish brown tint.

gj

 

Cool.. hehe.. I did a lot of research on plugs and found that one to be really good for the price, there are better like the denso iridiums and the Beru Silverstones (the best...) but for .89 cents you can't go wrong with teh bosch supers....

BUBBA

 

thanks for ya'lls input.........decided on Mobil One 10W30..on sale.....and the Bosch Super W9DC at $.99 each.