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.
Automatic Transmission Oil - ISUZU recommend DEXRON II automatic transmission fluid. It is acceptable to use DEXRON III where DEXRON II is not available but it is NOT acceptable to use ATF-G Borg Warner specified fluid as the shear properties are very different and transmission damage is possible.
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.