The following information has been transcribed from a 1977 Pontiac Parisienne Owner's Manual:


Engine Oil and Filter Recommendations


Under these conditions, change oil every 3,000 miles or 3 months, whichever occurs first.

 

See your Pontiac dealer for advice on the frequency of oil and filter changes under unusual driving conditions.

The above recommendations apply to the first change as well as subsequent oil changes. The oil change interval for your Pontiac engine is based on SE oils and quality oil filters. Oil change intervals longer than those listed above will seriously reduce engine life and may affect Pontiac's obligation under the provisions of the New Vehicle Warranty.

A high quality SE oil was installed in your engine at the factory. It is not necessary to change this factory-installed oil prior to the recommended normal oil change period. However, check the oil level more frequently during the break-in period since higher oil consumption is normal until the piston rings become seated.

Note: Non-detergent oil and other low quality oils are specifically not recommended. Only the use of SE engine oils and proper oil and filter change intervals assure you of continued proper lubrication of your Pontiac engine.

Note: SAE 5W-30 oils are recommended for all seasons in vehicles normally operated in Canada. SAE 5W-20 oils are not recommended for sustained high speed driving.


Recommended Viscosity
To help assure good cold and hot starting as well as maximum engine life, fuel economy, and oil economy, select the proper oil viscosity for the temperature range anticipated from the following chart:

Temperature Range Recommended Viscosities
Above 40°F SAE 30
Above 20°F SAE 20W-20, 20W-40, 20W-50
Above 0°F SAE 10W-30, 10W-40
0°F to 60°F SAE 10W
Below 60°F SAE 5W-30
Below 20°F SAE 5W-20

API SE is now obsolete and API Starburst oils are commonly available on store shelves, which means that Starburst Oils comply with ILSAC requirements . These oils have reduced levels of phosphorus (the anti-wear component of ZDDP) compared with the API SL, which could potentially be detrimental to flat tappet engines.

You should be using a Heavy Duty Engine Oil (HDEO) rather than a Starburst oil in your engine. Any HDEO (CI-4/SL or CJ-4/SM) has enough phosphorus to protect flat tappet valve trains. Starburst oils have enough phosphorus (up to 800 ppm) to protect OEM-style valve trains but HDEOs have more (usually 1000-1200 ppm). CI-4 HDEOs generally have more phosphorus than CJ-4 oils and would be slightly less expensive.

If you're in the southern USA where temperatures are consistently above freezing, you could safely use 15W-40 HDEOs in place of the 20W-40 oil specified in the manual. Otherwise, use a 30-grade HDEO (0W-30, 5W-30, 10W-30). Generally, 0W-30 and 5W-30 HDEOs are synthetics, which means they flow very well in extreme cold but maintain their hot viscosity better than 10W-30 and straight 30 in extreme heat.

There is no need to use a higher hot viscosity (second number in viscosity grade) than necessary as this just wastes power and fuel economy.

Notice that the factory recommended 7500 mile oil change intervals back in 1977 and this would have been with Group I oils that would be considered very low quality today. For those of you not feeling comfortable with going more than 5000 miles between dino-oil changes, you can use synthetic oil instead and time your oil changes to coincide with 7500 mile tire rotations. Many people on BITOG go 10,000 miles (~16,100 km) or more between oil changes using synthetic oil.