best choice for 142k mile 300zx

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May 26, 2004
Kingsland, GA
I have a 94 300zx with the VG30DE and showing 142k plus miles on it. It uses about 1qt every 1500 miles or so. I suspect most of the usage is actually leakage out of the rear main. Iam suspect of the rear main because I don't know if the pcv valves have ever been changed and they are a pretty big job to change them. I have been using Castrol 10w-30 and 10w-40 HM in it for about the past 10k miles. So, my question is would I be better off sticking with the current choice or going with something like Delo. I'm actually leaning towards Amsoil 15w-40 diesel (AME). Any advice or recommendations are appreciated. [Cheers!] thedawk
I've got an 85 300zx with the SOHC version of that engine that I use as my race car. I'm getting pretty good results with Mobil Delvac 1300 15w-40. Unfortunantly, I have no UOA's with it yet, but I will soon. [ June 24, 2004, 11:26 AM: Message edited by: Thomas Pyrek ]
Synthetic isn't a mechanic-in-a-can. It doesn't replace missing rubber or gasket material, or metal. My guess is that putting AMSOIL in won't solve your problem. Try a load of Auto-Rx. If that helps, then consider putting the AMSOIL in.
Auto-RX in a Mobil Delvac 1300 or Chevron Delo 400. Then once you get it clean and hopefully the rear seal leak slowed or stopped you can go to the Amsoil. Gene
I would change the PCV first and keep running the same castrol oil at a 3-4K mile OCI. See if the PCV change cures the oil leakage problem. If it does just keep using the Castrol dino. I wouldn't change to synthetic at 140K miles when you already have a leak.
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