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Z24i Engine Oil/Filter/Etc...


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Greeting, and salutations Ratsun.

 

So I (somewhat) recently came into possession of a (quite poorly treated) '86 720 4x4, and have just been using Castoral 10w-30 Synthtic High Mileage oil, save for the last change(which was actually a few days before I found this forum) where I used the Mobile 1 10w-30 Synthetic High Mileage oil since it was on sale.

 

Oh, and some High Mileage Lucas Oil Stabilizer.

 

However, from what I've been reading on here these oils lack the necessary amounts ZDDP required for older engines.

 

I've also read (thankfully before I bought one) that Fram filters are absolutely horrible/basically made of tissues or cheap cardboard these days, and that Wix/Napa/Etc filters...are several orders of magnitude better.

 

So, my first questions (but definitely not the last) on the forum are thus, what is the best oil, and filter for my engine?

 

Keep in mind that this thing does have over 250k miles on it, and that I live in California with all it's emission related fuckery, which I'm going to have to pass soon*.

 

Which means the diesel oil that many recommend both for the ZDDP and cleaning effects likely won't fly since that will unfortunately wreck the catalytic converter.

 

 

 

*The truck is currently in Nevada, since I was having a monstrous time finding an OEM exhaust manifold or a California legal header, since the original exhaust manifold was stolen right out of the back of the truck when my uncle (who owned it before me) was working on it.

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Don't forget the '85 is now 33 years old and was designed to run on the oils of 1985 not the oils being made today. 10w30 oils 33 years ago probably had much higher levels of zinc and the catalytic converters built then were not so sophisticated. Mainly they burned off excess hydrocarbons by injecting more air into the exhaust. Today's converters are much more elaborate.

 

I'm not a fan of synthetic engine oils. They are overly expensive and older Datsun engines simply don't need that much protection. I use 15w40 Shell Rotella T (I think renamed recently to T4?) It's been run in temps down to just below freezing but I recently saw it in 30w also. I drive mostly in the summer anyway. Chevron Delo 400 is also comparable and any oils marked 'Racing' also have higher levels and are also OK.

 

 

You can run any oil as a top up if you can't find the right grade. This is a long term preventative and today's oil won't wear out your cam or rocker arms if used to get you by till the next oil change. Idon't trust today's oil ZDDP levels and there's no harm running the higher level.  Yes the diesel oil has a higher detergent level also, all diesel oils do, so expect your engine to self clean more effectively.  If you have an old engine and are switching, expect the oil to appear dirtier much sooner after the first couple of changes. If extremely dirty engine perhaps change it again much sooner.  ALWAYS change the filter when you change the oil.

 

As to Lucas 'oil stabilizer' I never run additives because all oils have to meet or exceed  a minimum standard of quality and protection. Lucas and others rely on owners doubt to sell their 'snake oil' and would have you believe that you need even more protection. So just how much protection do you really need in a 100 hp 33 year old engine???? Well it's less than the oil you can easily buy anywhere. Change the oil and filter at the correct interval and keep the engine in good tune and you have nothing to worry about.

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After mulling it over I'll likely go for the Rotella T4 as you've suggested, since it'll help clean up the engine(which it needs) and keep it from wearing down any further(which it also needs considering the mileage).

 

Though I'm stuck on whether to get the 15w-40 or 10w-30, since even though summer is coming up I live in Tahoe, which likes to randomly throw snow/freezing temperatures at everyone as late as early June.

 

 

Any recommendations when it comes to oil filters, like say ordering an OEM one from Nissan, should I just get the best Wix one that will fit my truck, or some other brand?

 

 

...In hindsight, I probably should have just created a general thread for my truck in one of the other forums, since I'll be asking questions about it for a long time to come.

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So, I just installed a new gauge cluster since my old one was pretty borked thanks to the previous owner spilling coffee all over it, and almost everything works well, which is a nice change of pace considering the old speedometer would fluctuate between not reading at all and going to 60mph+ every other day, and the lights behind it were...not gone, but so dim as to basically not be there.

 

Definitely keeping the old one though, just in case the clock/fuel gauge/temp gauge on the new one stops working.

 

Who knows, might be able to refurbish it at some point.

 

 

But back to that 'almost', the tachometer still refuses to budge.

 

I'm guessing it's either the wiring or the resistor from what I've gathered online, but I can't really test the former and I have no idea where the latter is located.

 

 

 

....And the oil PSI gauge, which I've had negative luck finding the location of in the engine in all three of my owners manuals.

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The tach resistor is usually a small lump under the taped up harness around or behind the left (driver's) side headlamps and the coils. I think all harnesses have it there even if it doesn't have a tach option. If you add the tach is just .... works.

 

The oil pressure gauge is usually paired with a volt meter in a small housing just above the center console under the dash. 4x4 trucks have them and probably the ST 2wd and they may be an option on regular 2wd... I don't know. If you mean the sender for the oil pressure gauge, it's located under the intake on the side of the block between cylinders 3 and 4. The sender for the gauge is different from the sender that only lights the low oil pressure lamp in the dash. It will have two wires rather that the single one.

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My bad, I did mean the sender.

 

Guess I'll have to dig around and see where the guy before me stuffed the resistor then.

 

Hopefully it's that and not part of the wiring, which would be...irritating to go through to say the least.

 

Edit:  https://parts.nissanusa.com/nissanparts/index.cfm?action=replacement&siteid=14&groupid=E&sectionid=240&partcode=25950M

 

Would this be the right resistor?

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hy17J26.jpg

 

Would this be it?  Though I have no idea why there are two of them if so.

 

Or what the thing to the left of them appears to be, since it doesn't lead anywhere.

 

 

 

Edit:   It appears that my uncle lost the OEM down pipe/front pipe that went to the original exhaust manifold, or it got stolen along with said exhaust manifold.

 

Any idea where to find a new/used (California legal) one outside of here on the Nissan website?

 

I've looked around and while Walkers used to be legal, that hasn't been the case since 2009.

 

 

Edit2: It does appear that the resistors are gone/fried/corroded, and as I don't have any real electronic places in my town that might sell them, should I just order these from Nissan?

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The '84 FSM shows White/Blue and Black/Blue wires to the resistor so check which one has this and assume that is the tach resistor. Earlier models show Black/Red and  Black/Blue for wires. Anyway you only need one.

 

The round plug is for use by a Nissan dealership. A technician can plug the truck in to check some of the electrical components and diagnose problems.

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Both of them are White/Blue, which is rather the issue.

 

I'm guessing the guy before me fiddled with it a bit to do...something.

 

Maybe the detachable engine light located right past the coolant reservoir, haven't seen one of those in any other Nissan.

 

Interesting to know about that plug though, do they even do that anymore for trucks this old?  If so colour me surprised.

 

Though it does appear that the Nissan website is the only place that sells the resistors...besides one guy on Ebay, who wanted $30 for a used one.

 

 

 

So, going back to my other question earlier, is the only place online to get the  front exhaust pipe/front pipe/down pipe/the pipe that connects to the exhaust manifold/whatever...at the Nissan website?

 

Because I've looked around and that's the only place I can find a OEM/California compliant one, which is rather surprising since I thought there would at least be some used ones floating around.

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A down pipe is just a down pipe. It won't be, or not be, California compliant. All it does is collect and direct exhaust into the catalytic converter. Anything would do.

 

The diagnostic plug is on my '76 710 so probably before that even. BCDD, auto choke heater, ignition coil, several others. It's not at all sophisticated.

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...Oh, my bad

 

Was just being dumb and reading the catalytic converter warning the Walker Exhaust website had on ever page as applying to the piping as well without looking at the fine print.

 

In that case would the Walker brand suffice, or are there sturdier manufacturers worth the money?

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So I was replacing my oil pressure sending unit with a new one since the old one was so rusted/caked with sludge that I'm surprised it hadn't fallen apart, but I've run into something of a dilemma.

 

The old unit apparently had it's connectors in a T shape, while the new one is the same as a regular old plug.

 

Are there any adapters I could use for this, or will I have to cut/redo the wires up on either the sending unit or the plug leading to the gauge?

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The old one has two wires, one for the pressure gauge and one for the red warning light in the dash. If you have the gauge get the right sender with two wires. If not put a connector on the end and connect up the red warning light.

 

You need this one...

3p3Ippk.jpg

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The Old Unit:

HIT5oKx.jpg

 

 

The New Unit: s-l300.jpg

 

 

What I was (poorly) trying to ask was if there was an adapter that would work with the latter image to fit a female T shaped connector, or if I should just redo the wiring on either the old connector leading to the gauge/light, or the new oil sending unit using some spade terminals.

 

 

 

On a side note, I'm left wondering why my old one looks so different from all the new ones.

 

And you would not believe how hard it was to find under all the...well, layers and layers of grease/dirt/I don't even want to know.

 

At first I thought it was part of the engine itself, and wondered what it did as well as what the wiring led to, but after consulting my books for the tenth time it appeared that no, it really was the oil pressure unit.

 

Just, y'know, absolutely buried under a massive layer of crap.

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That one is not for the older Z24 or Z24i in the 720. I don't know what it's for.... perhaps the Hardbody? or something after '86. The one I pictured was used in the 720, S110, 300ZX and the S12 through 86.5 at least, or any vehicle with an oil pressure gauge roughly between '80 and '86.

Yes they look similar and you could probably just trim the connector off and solder it onto your engine harness. You'll have to figure out which wire is the gauge or red light.

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Good to know, shouldn't be too hard.

 

But yeah, I'm pretty sure the guy who owned it before me or my uncle did messed with the wiring something fierce.

 

He was a mechanic, but apparently a terrible one judging by the state of the truck when my uncle first bought it.

 

Edit:  Success!

 

Took a bit of finagling, but I can finally see my oil pressure.

 

Very happy the gauge wasn't also toast.

 

Though I'm at a loss on how to tighten the sensor with a wrench/whatever after getting it as far as I (carefully) could by hand.

 

It doesn't appear to be leaking at the moment, but I'll wait a bit and see if it starts to.

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