by Lorne M. Goldman

The V-8 engine relies more on oil volume than oil pressure. So the oil doesn't have to have extreme temperature or pressure capabilities. So use of synthetic or semi-synthetic oils is not necessary and a waste of money. If you use your car as an everyday car and plan to keep it with the same engine for a long time, then frequent 3000 mile) oil replacements will have a better effect on your engine than using expensive oils.

A somewhat thicker standard oil doesn't hurt so 10W40 or 20W50 is a good option. The Buick lifters were made for 20W50 and Rover/LR kept using the same lifters. Make sure though that you use an engine oil with good detergent qualities, particularly for the V-8's as they tend to be very sensitive to oil sludge. Castrol Longlife is good..subject to the ZDDP codicil.

Standard synthetic Mobil 1 5W50 is a great sysnthetic with plenty of ZDDP, if you want to use synthetic anyway.

In the manual it is stated for the older models that oil changes should take place every 5000 miles. For later models it was set at every 12,000 miles, but this figure tends to be very inadequate and wildly optimistic if you want the engine to last as long as you do. As a rule of thumb an interval of 3000 miles or every year (whichever comes first) should be used.

Change the oil filter at the same time you are changing oil. Some people only change the filter after every second oil change. Normally it won't hurt but then it's easy to forget it the second time also! and the cost of a filter isn't that big. Another reason is that the amount of flow pumped out by the oil pump reduces when the filter is becoming clogged. As noted, this V8 needs copious amounts of oil to keep it well lubricated so it is better not to count beans on this point and just change the filter together with the oil.
WATCHPOINT: If your engine is used for short distances, or you expect a lot of sludge and such inside the engine, you can try the following trick. Before changing the oil. Drain some engine oil (about 1 litre) and top up the oil level with 1 litre of ATF oil (Automatic Transmission Fluid). ATF oil has very good cleaning properties and does a good job of internally cleaning the engine. Leave it in for about 100 miles in the engine. Then drain all the oil and refill with normal engine oil. It will certainly help a lot.

WATCHPOINT: Forgive me for warning about the obvious but a synthetic oil should NEVER be mixed with a non-synthetic motor oil.


A few years ago, motor oil companies began reducing the amounts of ZDDP. ZDDP or zinc dialkyldithiophosphate, was the most common anti-wear agent used in all motor oils for decades.

A few years ago, the US government decided that it would require auto manufacturers to guarantee a 150,000 mile lifespan for catalytic converters by 2009 (100,000 for 2004 and 120,000 for 2006).  The EPA offered vehicle manufacturers "credits" for early implementation as well as penalties for violation of these standards. Over a long period of time (100,000 miles), ZDDP can coat the cats and reduce their effectiveness. Automotive manufacturers have pressured their oil suppliers to remove substances from motor oils that would shorten the service life, including the proven EP (extreme pressure) additive ZDDP.  The oil companies responded by lowering or removing ZDDP without informing the public.

Sadly, ZDDP is necessary to flat tappet engines...i.e Triumphs and Rover V8s 1968-2004. The Rover V8 was one of the few flat tappet engines left on the road. So far, it has been irrefutably determined that the absence of ZDDP can cause tappet and camshaft damage when breaking in a new engine, flat tappets or flat tappet cams. Camshaft suppliers to these engines now recommend a special lubricant for the breaking in period that contains sufficient amounts of ZDDP.

Long term damage without ZDDP has not be determined. Nonetheless, it is better to be safe than sorry.  Maintain a minimum level of .13% ZDDP in your oil. That can be done by adding GM's Engine Oil Supplement or  ZDDPlus, the amount of which will vary with the motor oil you choose.

Priming the V8 oil pump

There is a sad characteristic of the Buick/Rover oil pumps. They can lose their prime, thus leaving the engine without a lubricating oil supply, which leads to a major engine failure in a minute or so. That being said, in the many many times I have dealt with these oil pumps I have seen one lose its prime once and that after the pump was out and in pieces for weeks. However, it is better to be safe than sorry.

When there is air in the oil pump it will be compressed and the pump will not pump out oil and no oil pressure will be indicated. Don't run the engine when this happens! The pump has to be primed.

There are three ways to do it:

1. Packing the Pump With Vaseline (aka Petroleum Jelly)

Drain the oil and unscrew the oil filter
Unscrew the six bolts from the pump cover.
Fill the cavities between the gears with vaseline
Fit a new gasket and refit the bolts (torque down to 10-15 lb/ft)
Replace the pre-filled oil filter and top up the oil
Start the engine and check for oil pressure and leaks.

2. Turning the Oil Pump Drive Gear

Remove the distributor. Make an adapter to fit the oil pump drive gear
and using an electrical drill, turn the the drive gear until the pump primes.

3. Packing the Pump with Vaseline Using a Grease Gun
by John Sheally II for the eMog Pub

Fill a cleaned out standard grease gun with one half pint of Petroleum Jelly
Leave the standard grease connector tip on the gun. (for zerks or grease nipples)
Remove the Oil Pressure Relief Valve Plug
Extract the Spring from the relief valve.
Insert the grease gun in the housing fill with the half pint of Jelly.
Replace spring and plug and you have a direct well packed oil pump gear housing. with no mess.

Oil additives

Aside from the codicil above about ZDDP, please forget them oil additives!! For example Slick 50 isn't paying back millions of dollars back to customers for nothing. The firm isn't even allowed to advertise that it's products reduce wear!!...this should say enough. Teflon additives tend to block the small oilways and clog up the oil filter doing more damage to the engine then you imagined.

V8 Oil pressures

Warm 27-35 psi at 2600 rpm. Warm 15-20 psi when idling

If the pressure gauge shows nothing and the oil pressure light doesn't show up you've still got around 7 psi left of pressure. Stop the engine and check for the reason the gauge shows so little pressure. If the engines start to rattle then immediately stop the engine because the oil pressure is so low it isn't enough to keep the hydraulic lifters pressurized.

You have to seriously start thinking about a rebuilt when the pressure drops to around 20 psi when running at 2400 rpm with a warm engine. Oh! and remember the bi-metal oil pressure gauge on the dash isn't the most accurate instrument there is. So before rebuilding take a reading with a proper oil pressure gauge!

Oil Change Standard Procedure

Oil Change Safer Procedure

No oil change method is foolproof here but if you change oil and use this procedure there is less chance of having to prime the pump. However old and new oil will be mixed a tiny bit.