Z32 Best engine oil

Discussion in 'Technical' started by Darren Foy, Mar 11, 2021.

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What is the best engine oil to use in a Z32 TT

  1. Penrite

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  2. Full synthetic

    2 vote(s)
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  1. MikeZ32

    MikeZ32 das Über member

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    In Aussie manual too? Or the global market manual.

    Isn't 10w30w just a general recommendation for the cars that have to survive cold weather starts and some summers? Australian winters are mild and don't require that thin IMO.

    Also our cars are getting on in age, the tolerances in the engine are getting bigger too, I run a 15w40 or 20w50 for most of my old jap clappers, unless the car is newer (less than 15 years or under 150,000kms) then I stick to whatever the manual says.
     
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  2. ryzan

    ryzan Black Mesa? Fat chance...

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    Manufacturers have been trying to run the thinnest oil possible for decades as it's a relatively easy way to eke out the best fuel economy numbers possible. They're more concerned about selling cars today rather than how the engine will perform in 20 years time with a thin oil. Valvoline on their website actually discourage away from running a thicker oil in higher mileage engines, instead opting to use different addatives. Though I'm not sure how much of that is just marketing vs. an actual added benefit (ie. increase the detergent content so you can say it helps keep the engine 'clean', slap a high mileage sticker on it and send it out the door).

    You also have to remember that thickness and properties vary between manufacturer as oil weight ratings are essentially just a range that it has been found to perform in (the viscosity ratings in their data sheets). Based on where the cutoff is, you could have a 30 weight oil and a 40 weight oil that have a more similar viscosity rating than two different brands/blends of 30 weight oil.

    With that said, modern engine oils have come a long way from where they were back in the 80's when Nissan designed the VG30. The Aus spec manual does say 10w30 is preferable also, though I'd say that was more for the fuel economy benefits rather than 30+ years of engine lifespan. Honestly, the requirements for a VG30 (like most engines of that era) are pretty minimal considering it will take just about anything from a 10w30 to 20w50 so as long as you stay within that range you'll be fine. Let's face it, most NA's aren't really getting driven all that hard and TT's had a factory oil cooler to help compensate for what isn't a particularly large sump. Personally though, I don't see why you would bother when there are 10w40 or 10w50 options on the market.

    Please don't take anything I've said as gospel though and do your own research as I'm not an expert. I spent a lot of time reading and researching oils years ago when I had a D40 Navara since they were 'internet famous' for snapping timing chains. Since the top chain was dual row and the bottom chain only a single row, general consensus was that the bottom chain was too weak and designed to fail, however this always perplexed me since it's geared down at a 2:1 ratio. From the research I did it seemed most people having timing chain issues were also the ones who ran a thicker oil because they thought the factory fill 5w30 was too thin for Australia. When I pulled mine down I found that the two chains shared an oil squirter on the reduction gear (Nissan actually superceded the original oil squirter with a different one that likely increased flow) so it would make sense that if the chains weren't getting sufficient lubrication ie. from someone running 15w50 they'd suffer premature wear, and this is where the single row would fail first. After 200,000km+ on 5w30 I measured both chains in my D40 and found both were well within factory spec, though surprisingly the single row chain was much better than the double row.
     
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  3. Darren Foy

    Darren Foy New Member

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    Thanks again guys, and yes your right first v6 turbo I have owned let alone an import. The car shows 101000kms on the clock and by all appearances it looks right. So I am going to use a 10w40 full synthetic oil. Thanks again guys for all the useful info.
     
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  4. MickW

    MickW Carntry member...

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    Great post mate, and that's really intriguing about the Navara chains.
    And this is why even 10 years ago we all groaned about "which oil?" threads.
    Hah, several years ago Valvoline were selling 20W60 for high mileage engines. I tried it, worked great for maintaining pressure on a stinking hot day climbing small mountains during Zed cruises. But they don't seem to sell it any more.
    Here's a bizarre thing, and you'd have to do some thread archeology to get more details but the short version is that engine oil only gets sent to the front mounted cooler when it exceeds a certain pressure and opens a bypass valve. The actual pressure doesn't seem to be stated in the FSM, and the Gurus from 10 years ago were not certain about the pressure. So when your TT's oil is hot and thin and needs cooling it might not get sent out to the cooler because it doesn't have enough pressure to open the bypass valve. Hence the market for theromostatically controlled "sandwich plates" for the TT oil filter coupling, it would allow oil to flow to the cooler based on temperature rather than pressure.
    Somebody please school me up if I'm wrong.
     
  5. ryzan

    ryzan Black Mesa? Fat chance...

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    The stock oil cooler really isn't a bad design like most people think it is. Oil pump bypass opens at around 60psi and engine is making this pretty much whenever it's driving around. So the oil cooler pressure valve wouldn't be anywhere near 60psi otherwise it'd never open up. So pretty much whenever you're driving it will be moving oil through the system, which is actually pretty clever as it won't pump oil to the cooler when you are idling, as this would only aid in heatsoaking the radiator which is already at its limits while not moving.

    With that said, the cooler is definitely on the small side although the European TT's got a much nicer stock oil cooler. The other thing to take into consideration is what volume of oil is going to the cooler, though the fact they fit an inline restrictor makes me think it's almost certainly getting plenty (enough for them to actively slow it down).
     
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  6. zx299

    zx299 Well-Known Member

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    The inline restrictor in the cooler line serves two purposes …… it restricts the free flow of oil into the sump to prevent engine starvation, and slows the oil flow through the cooler so it has more time to cool :cool:
     
  7. ryzan

    ryzan Black Mesa? Fat chance...

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    The stock pump is more than capable of putting out sufficient oil pressure even when the stock cooler is bypassed with a piece of hose and no restrictor fitted, you'll probably find the oil tree is a bit of a restriction on its own. Far from ideal but you'd probably be surprised how many engine swapped cars are getting around like that.
     
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  8. MickW

    MickW Carntry member...

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    Thanks again ryzan. I'd not refreshed my Zed knowledge for about 10 years now, nice to know someone is still on the case :)
    * For the listeners in - ryzan is describing the oil pump over pressure / bypass valve. Not the valve which allows flow to the cooler.
    The FSM shows normal pressure to be from 51 to 65 psi @3,000 RPM.
    I suppose the FSM variance is to allow for oil temperature, viscosity choices, engine wear, pump wear etc.
    But that's a 14 psi difference and the median figure is 58 psi. Not sure what the % variance is but it's not small.
    Which takes us back to the question of "which oil?" Seems there's a lot of latitude for choices there...

    Anyway, so the cooler check valve would need to be comfortably lower than 51 psi to be any use, keep in mind that any oil which is struggling to maintain a healthy pressure probably needs more cooling.
    But I've yet to find the actual pressure at which the oil cooler valve opens. Maybe I need to troll the Concept Z and Z1 sites again.
     
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  9. ryzan

    ryzan Black Mesa? Fat chance...

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    Interesting point about the nominal oil pressure range in the FSM. It doesn't appear to distinguish between NA and TT which apparently have different springs fitted to their (oil pump) bypass valves. So I'd say the lower range would be NA and higher range TT.

    The only (vague) reference I could find for the stock cooler is that it is supposed to open above 2000rpm, I'm not sure how accurate that is but it does seem reasonable.
     
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  10. MickW

    MickW Carntry member...

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    tldr: 47 - 53 psi

    I finally found Nissan's pressure specs for the TT oil cooler circuit, in the 1994 service manual. Along with an oil flow schematic which actually includes the cooler. Check out pages LC4 and LC5 in the 1994 and 1996 FSM. I'd been working from the FSM for the 1989 built cars because, 1989 built. That FSM doesn't even include the cooler in the schematic let alone the working pressure.
     
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  11. yellow300zx

    yellow300zx Pimpin Ain't Easy

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    All good, I've seen it many times. :)

    Numerous mechanics on here have said it before over the past decade or more. So unless you are in Melbourne (or similar) in winter the 10w-30 is not really suitable.

    If you look in the manual, also it states for example "5W-30" should only be used on turbo engines in extremely cold conditions." So 10w30 isn't much different.

    For hot areas it states (which all our places get in Australia) 20w-40 or 20w-50 is suitable.

    This also echoes like I mentioned all the blokes who used to rebuild the zed engines here on the forums.
     
  12. SRB-2NV

    SRB-2NV #TEAMROB

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    Penrite 15w50 fully synthetic for my 300+rwkw nugget.
     
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