Oils aint Oils...

GeminiCoupe · Post by **GeminiCoupe** » Mon Mar 13, 2006 10:01 pm

Got a pretty trivial/useless question but anyway...engine oil for 4ZC1 Turbo. What should i run? Ive got HPR5 in there atm which is a semi-synth 5-40W, seems O.K except that there is alot of valvetrain noise at anything above idle speed [900-1200rpm]. Im under the assumption that my rockers are slightly rooted, but would i be able to run a heavier weight oil to keep em quite? Say 25-50W or the Penrite Turbo oil [15-70W]?

Nick-

Bugle · Post by **Bugle** » Mon Mar 13, 2006 10:09 pm

I've always run 20/50 that's the thickest oil it says you can use in the service manual. It also says to not use synthetic.. No valvetrain noise at all once it's warmed up. Have you adjusted the clearances lately?

GeminiCoupe · Post by **GeminiCoupe** » Mon Mar 13, 2006 10:27 pm

Have i adjusted the clearances EVER? It sounds too loud to be just as simple as that, although i was planning to adjust them. I gather clearances are in the service manual?

I really should buy one...someday..

Nick-

Bugle · Post by **Bugle** » Tue Mar 14, 2006 12:06 am

They can get pretty loud when they're out of adjustment..
Same as Gemini 0.15 inlet and 0.25 exhaust.

IZU069 · Post by **IZU069** » Wed May 10, 2006 1:18 am

Be careful with thick oils.
A mate seized at least 3 DOHC engines that I know of (often big ends). Yeah - generally impossible for Isuzu unless running over redline without oil and water - refer to various engine blow-up competitions; Isuzu are often record holders with over 1.5 minutes (and old Chev Luv) etc with the next best lucky to last 30 seconds.

Turns out he was using Penrite HPR-50. This is okay for sloppy shit engines or high-volume low-pressure systems (eg; okay for Harley and Ducati motorbikes; I'm not saying which is the shit engine).

The key issue was his hi revs - he was not known for taking more than 90 minutes on a certain 2.5-hour freeway trip.
The oil was simply too thick to get enough to the big-ends etc at those revs.

The same is likely to apply to (presumably) tighter tolerance Piazzas, turbos etc.

If the engine (oil pressure) is okay, stick to the recommended rating (usually 20W-40 or 50?; depending on climate etc). Use a thick oil only if oil pressure drops excessively (eg idling with worn big-ends etc).

Don't panic with (say) 20W-50 etc - this means "its 50W when cold; 20W when hot". So don't rev too high when cold (though the above engines seized way after warm-up). HPR-50 is always thick - I can't remember if is a straight 50W or something like a 40W-50, but it's too thick for hi-reving tight engines.

FYI - I don't use synthetics - even if they last 200,000km, I'd rather change oils more often to remove contaminants (condensation, metal & sht).
For older engines, I'll use (eg) Castrol GTX-2 and not the later GTX-3's etc which are more suited to modern multi-valve engines. Mind you, on my old Isusus I wouldn't use any detergent oil (Castrol CX etc) except on a clean (rebuilt) engines (after running in) - but that's another story.

And let any "new oil types" have a few years in the market. I remember the "revolutionary" graphite engine oils that came out. You don't see them any more do you? Quite a few personal budgets suffered from that "revoilution".

Cheers, Peter (IZU069)

dbraiki · Post by **dbraiki** » Wed May 10, 2006 11:14 am

I found this info on a british Piazza website. It may help;

Engine Oil - ISUZU recommend a 10W/30 NON-synthetic oil for use in the Piazza although a 10W/40 works just as well. Oil technology has advanced since the Piazza was developed and semi-synthetic oils are now about the best product to use. FULLY synthetic oils should be avoided, especially those with a viscosity rating starting 5W or 0W as they are far too thin to provide adequate protection upon startup. REMEMBER - when the 4ZC1 engine was designed, such oils did not exist, therefore the lubrication system was specified for thicker lubricants.

Manual Transmission Oil - ISUZU recommend using 10W/30 ENGINE oil in the 5-speed manual transmission, to be changed at 24,000 mile intervals. Many people are oblivious to this, hence Piazzas tend to suffer from transmission whine. 10W/40 engine oil can also be used, as can additives such as Slick 50 and Molyslip.

Rear Axle Oil - ISUZU recommend EP80W/90 (GL-5) hypoid gear oil for non-Limited Slip Differential equipped cars (some Lotus manuals and ALL automatics - on manual cars check for the code "G80" on the options plate riveted to the firewall). For manual cars equipped with a Limited Slip Differential, these can be serviced using Castrol Hypoy LS.

Brake & Clutch Fluid - ISUZU recommend DoT3 standard brake & clutch fluid. It is permissible to use DoT4 and DoT5.1 also, but the different types should ideally not be mixed. THE USE OF SILICONE BRAKE FLUID IS NOT RECOMMENDED FOR THESE CARS.

Coolant/Antifreeze - ISUZU recommend using a 50/50 mix of good quality Ethylene Glycol Antifreeze and deionised/soft water, to be drained and replaced every 12,000 miles. This helps keep the cooling system in top condition and can help avoid the cooling problems the Piazza is known for.

Power Steering Fluid - DEXRON II or DEXRON III automatic transmission fluid.

Bugle · Post by **Bugle** » Wed May 10, 2006 1:37 pm

Yeah that's because poms live in the freezing cold

Here are the charts in the manual as you can see you need thicker oil for summer in most of Australia (maybe not Melbourne unless it happens to not rain).

speedracerles · Post by **speedracerles** » Wed Jun 11, 2008 11:59 pm

In my car the oil temp is sitting at 115 past the line what does that mean? when it Ideals its at like hafe way but when I take off it goes back up again... I need help thanks

Post by **Virtual-R** » Fri Jun 13, 2008 6:59 am

Might be dodgy wiring, otherwise you could need a decent oil cooler installed.

If the temperature appears to sit mid way on idle, but the second you put your foot down it jumps above the mark id say its more a wiring issue than anything else. Might be time for a new sender.

IZU069 · Post by **IZU069** » Sat Jun 14, 2008 1:27 pm

I'd agree with the wiring or charging fault.
Whilst fuel & temp gauges go through a voltage regulator, the oil pressure gauge doesn't. [This Volt Reg is mounted behind the gauges. Output is typically 8V but it's usually mechanical/bi-metal and switches between 0 & 12V to give an 8V average.]

It might be the same with the oil temp and hence its gauge could vary with engine RPM - especially if you have a weak battery or charging system. (Is this a st'd fitted gauge or aftermarket? Should I know - I have two 1986 Piazzas - aka Garden Gnomes? I assume the 115 is Fahrenheit?)

I have a Nissan N13 type Bosch 70A alternator in my Wasp. It outputs 14.5V at idle and upwards even with headlights on.
But often systems will dip below "normal" alternator output (14.4V) at low revs. This can be the alt/regulator, or because the battery is old and therefore tends to sit below 12.6V and take more current. (A fully charged battery is usually 12.6V and will take very little current even when "charging" at the alternator's 14.4V ouput.)
I have seen voltages dip to under 12V at idle speeds. (Most gauges then "go down", but some can go up.)

As to real oil temp, it won't change too quickly.
And if the oil does overheat, you should see a jump in water temp (since oil does a lot of cooling - say 40/60% oil/water cooling) assuming you haven't hotted (no pun) the engine etc.
Your problem sounds like it is alternator voltage related.

speedracerles · Post by **speedracerles** » Tue Sep 09, 2008 11:42 am

Well for the last few weeks my car has been making a clicking sound when I accel, on the gas. I dont

know what that is... someone told me that it could be my lifters needing a good ajustment. I dont know

how to do that so if anyone could coach me then that would be great. Hit me back

madmike · Post by **madmike** » Tue Sep 09, 2008 4:09 pm

depends what sort of clicking sound it is dude.
Could be a million things.

Lifters would be really loud at cold idle if that was the problem 4z motor is known to have noisy lifters when cold..

Could be the gearbox, wheel bearings, diff, driveshaft, turbo starting to go, small stone in tyre...... the list goes on.

A bit more info may help.

IZU069 · Post by **IZU069** » Tue Sep 09, 2008 5:01 pm

speedracerles wrote:In my car the oil temp is sitting at .... when it Ideals its at like hafe way but when I take off it goes back up again
....&...
... it could be my lifters needing a good adjustment. ... so if anyone could coach me then that would be great. Hit me back

Are you sure you weren't looking at oil pressure since it decreased at idle? (If not, then poor voltage regulation, bad connections or electrical interference seem likely.)

As to adjusting the valve clearances I suggest you get a good DIY book etc.
Assuming they are screw-adjustable - in brief - when cold remove the cam cover & measure between rocker & top of valve (stem). Clearances should be 0.15mm & 0.25mm for inlet and exhaust respectively.
If adjustment needed, undo the 12mm hex locknut, adjust screw, re-lock locknut. The feeler gauge should provide a firm resistance to feeler movement when correct.
The valves are done in cylinder order 1-3-4-2 (1/2 crank turn in between) when the respective piston is TDC on the dead stroke - eg, 1 crank turn around from where the rockers' lifts "overlap" when cranking. Start with cyl #1 and finds its TDC alignment.
Removing the splugs first makes engine rotation easier.

In anticipation of the next "what is...".

Cheers.

mauriziomerli · Post by **mauriziomerli** » Sun Dec 07, 2008 10:31 am

I use Fuchs 10W \ 40 semi synthetic oil, it's £11.99 from GSF from 5 litres.

Has quietened down my clacking valvetrain but I think it's still a fair way out of alignment.