Questions and Answers

A Motor Oil Question Q. I drive a 1991 Ford Thunderbird (V-6 - non-supercharged). It has 142,000 miles and has just recently had a new head gasket installed (not sure if that is pertinent info). My question is:

"In hotter temperatures in San Diego County (up to low 100's in the summer time), should I go with a thicker oil (i.e. 20W-50) or a thinner oil (i.e. 0W-30)? My guess is thicker because as the heat goes up, the higher viscosity oil will be better at protecting the engine rather than a thinner one thinning out even more as engine and climate temperatures rise.

Will synthetics help as most claim they may keep your engine temps a little cooler than conventional oils? Also, will the thicker oil help by lessening the burn off as common with older engines?"

Sincerely,
Brian

A. There would be, in my opinion, no harm using a 20W-50 oil in your engine. I use 1 15W-40 in mine year round. The down side is you may notice a drop in fuel milage. But according to Ford:

ISSUE:
Ford Motor Company now recommends SAE 5W-30 viscosity grade for servicing any Ford gasoline-powered vehicle regardless of model year.

ACTION:
When servicing any Ford gasoline-powered vehicle, use SAE 5W-30 viscosity grade motor oil. Refer to the following text for further details.

Both SAE 10W-30 and SAE 5W-30 viscosity grade motor oils have been recommended in the past depending on vehicle model and model year.

Tests have proven SAE 5W-30 viscosity grade motor oil provides the optimum protection and benefits for Ford gasoline engines. At both high and low ambient temperature conditions, SAE 5W-30 provides the best overall protection. It allows faster starts under cold ambient temperatures.

SAE 5W-30 also provides approximately 1/2% increase in fuel economy over SAE 10W-30.

SAE 5W-30 viscosity grade motor oils certified for gasoline engines by the American Petroleum Institute (API) should be used for all service procedures requiring replacement of the motor oil.

Additional Information provided courtesy of ALLDATA