Newer engine - switch to synthetic?
 

Hi all,

I just bought a 1993 300zx with 144k. I just found out however that the engine was replaced with a brand new one at 90k! talk about a good find. I was wondering since the car has lower miles on the engine (I figure 54k) if it would be a good time to switch to full synthetic. I just really don't want to spring any leaks since it does not have any right now.

On another note, When I do start the car it will jump up to about 2k rpm like normal, but will then stumble a bit for a couple seconds, and finally go back up normally. The engine runs perfectly otherwise. Could that be from dirty or clogged injectors? Thanks in advance!

I would switch, and unless your absolutely flogging the living daylights out of it,(road racing) I'd go with as light of oil as reasonable. I use 5w30 in an all aluminum 4 cam v8 with 135k on it, and when I switched the thinner oil pumps up so much faster in the morning that I lost nearly all timing chain rattle. Your long past the break in period to switch to synthetics, and I don't think those engines are leak prone anyway.

I doubt highly your fuel injectors are causing that, although it's never a bad idea to run some injector cleaner through it.(I use SEAFOAM) Idle air controls are famous for getting jamed up with crud though, and I'd give that a good inspection/cleaning.

look into testing and cleaning your idle control valves on that starting issue.

as for oil, it's really a personal call. i know an engine builder that swears by napa brand oil, another engine builder that swears by mobil one, and tons of car enthusiasts that go for anything in between. it's really your call. the switch to synthetic in my opinion might not be the best idea, because if you ever change your mind about it, there are those that will say that it's a bad idea to go from synthetic back to conventional. i've done it with no problems though. do a search on any car forum for oil and you'll just come up with argument after argument.

lol napa brand oil is made by penzoil, just like napa gold filters are made by wix.

i thought it was valvoline? or is that the same too?

penzoil if i remember correctly... but now you have me doubting myself, but penzoil n valvoline are not the same. i'll check when i go into work today. lately though ive been having alot of issues with napa stuff. only thing that hasn't been an issue is their batteries and oil filters since wix is a good company. but only their gold filters. also alot of their engine parts are made by clevite. their other stuff though, most of it has been problematic for me. typically electric motor based things, and their oil pressure sender unit for my talon is crap.

Hm. Lol I haven't heard much out of you in a while. I get all my generic parts from advance auto. They all seem pretty good. They'll be 1/3 the price of courtesy's and still have a warranty often

+1 on valvoline

Ended up putting mobil 1 full synthetic in a week or so ago. no leaks yet...

Sort of update, I finally got my red line in the mail for the transmission and rear diff. Going to the auto hobby shop now to put it in. Hopefully the filler and drain plugs aren't too hard to hard to get out. Now all I need to do is find my hand pump

i hope they aren't hard to get out too....

what is the proper tool for that? i used the 1/2" drive breaker bar with... success... it could have gone better though.

Turned out to be easy as pie. I used breaker bar with a 3 foot handle and they came off without any complaining. I did, however, run a little short of fluid. I only bought three bottles of mt-90 and one of the gear oil from red line. I ended up having to top off the differential with a little mobil 1. All in all, not a hard thing to do at all.