ZR-1 Preventive Maintenance

 Attention to these items can help avoid the nearly inevitable problems that can occur if the maintenance is deferred for a very long period of time.

 

·        Oil change and lubricate the front suspension. $67. plus oil and filter. Preference for a particular oil and filter can be fulfilled. We recommend Amsoil AMO 10W-40 SG, $12.82/quart. We recommend the Bosch 3401 filter, $8. Complete oil change with 9.25 quarts of oil $194.

 

·           Pressure flush the brake fluid. DOT 3 synthetic fluid is recommended for street driving. For racing, we match the type of fluid that is in use. For fresh racing preparations, we recommend Motul 600 DOT 4 fluid. This should be performed every three years. $119 with DOT 3 fluid.

 

·           Remove the thermostat and pressure flush the engine cooling system. Reverse flush the heater core. Install a new thermostat. Refill the system with OE type green coolant. Remove the overflow bottle and clean the inside. This should be performed at four year intervals. $216.

 

·           '91- '95. Flush the clutch hydraulic system. This should be performed every two years.  $54.75.

    '90 OE clutch slaves do not have a bleeder valve. For '90's, we remove the fluid from the master cylinder reservoir and clean the reservoir and refill.  $28.

    We use synthetic clutch specialty fluid.

 

·           Replace the transmission lubricant. We recommend Amsoil MTF synthetic 5W-30. This lubricant meets or exceeds the GM specifications for the OE PN 1052931 lubricant. This should be performed at 50K miles intervals. $110.

 

·           Replace the rear axle lubricant. We use Amsoil SVG 75W-90 synthetic lubricant. We add the Amsoil limited slip clutch friction modifier additive. Perform this service after the gear set has completed the first 1,000 miles. Then after 100,000 miles.  $103.

 

·           Flush the power steering fluid. We use Amsoil synthetic fluid. This should be performed at five year intervals.  $46.

 

·           Tighten the oil pan bolts. This will extend the life of the gasket. Loose bolts contribute to the deterioration of the gasket. About half of the bolts are easy to access. They should be tightened at oil change intervals or once a year. Tighten the open access bolts.  $25.

     All of the bolts can be tightened if the heat shields and braces are removed for access. This often reduces leakage by 90%. We also tighten the cover for the oil pressure regulator. Tighten all of the bolts.  $200.

'90. All of the above without tightening the oil pan bolts. $816.

'91-'95. All of the above without tightening the oil pan bolts. $843.

We believe that the best spark plug available for the LT5 is the Denso IT20TT, also known as part number 4714. This spark plug is designed specifically for the LT5s wasted spark ignition configuration. It is iridium and platinum tipped. Carefully gap the plugs to .045" while avoiding contact with the delicate wire tip on the strap. This plug will wear for at least 30k miles. It is a tapered seat plug.

The Denso K20PR-U, also known as part number 3145 is a simple copper design plug like the OE plugs that were on used on the '90 - '92 engines. The cost is lower and it will wear for about 10k miles. It is a gasketed plug.

About LT5 spark plug seats. All LT5s were machined with tapered and gasket seats. Tapered or gasketed plugs can be installed in any LT5 engine. 

Revision 33    19-Apr-25