How to Choose the Right Motor Oil

Brand V.I. Flash Pour %ash %zinc
20W-50
AMSOIL 136 482 -38 0.5 n/a
Castrol GTX 122 440 -15 0.85 0.12
Exxon High Performance 119 419 -13 0.70 0.11
Havoline Formula 3 125 465 -30 1.0 n/a
Kendall GT-1 129 390 -25 1.0 0.16
Pennzoil GT Perf. 120 460 -10 0.9 n/a
Quaker State Dlx. 155 430 -25 0.9 n/a
Red Line 150 503 -49 n/a n/a
Shell Truck Guard 130 450 -15 1.0 0.15
Spectro Golden 4 174 440 -35 n/a 0.15
Spectro Golden M.G. 174 440 -35 n/a 0.13
Unocal 121 432 -11 0.74 0.12
Valvoline All Climate 125 430 -10 1.0 0.11
Valvoline Turbo 140 440 -10 0.99 0.13
Valvoline Race 140 425 -10 1.2 0.20
Valvoline Synthetic 146 465 -40 1.5 0.12
20W-40
Castrol Multi-Grade 110 440 -15 0.85 0.12
Quaker State 121 415 -15 0.9 n/a
15W-50
Chevron 204 415 -18 0.96 0.11
Mobil 1 170 470 -55 n/a n/a
Mystic JT8 144 420 -20 1.7 0.15
Red Line 152 503 -49 n/a n/a
5W-40
Havoline 170 450 -40 1.4 n/a
15W-40
AMSOIL 135 460 -38 <0.5 n/a
Castrol 134 415 -15 1.3 0.14
Chevron Delo 400 136 421 -27 1.0 n/a
Exxon XD3 n/a 417 -11 0.9 0.14
Exxon XD3 Extra 135 399 -11 0.95 0.13
Kendall GT-1 135 410 -25 1.0 0.16
Mystic JT8 142 440 -20 1.7 0.15
Red Line 149 495 -40 n/a n/a
Shell Rotella w/XLA 146 410 -25 1.0 0.13
Valvoline All Fleet 140 n/a -10 1.0 0.15
Valvoline Turbo 140 420 -10 0.99 0.13
Brand V.I. Flash Pour %ash %zinc
10W-30
AMSOIL 142 480 -70 0.5 n/a
Castrol GTX 140 415 -33 0.85 0.12
Chevron Supreme 150 401 -26 0.96 0.11
Exxon Superflo Hi Perf 135 392 -22 0.70 0.11
Exxon Superflo Supreme 133 400 -31 0.85 0.13
Havoline Formula 3 139 430 -30 1.0 n/a
Kendall GT-1 139 390 -25 1.0 0.16
Mobil 1 160 450 -65 n/a n/a
Pennzoil PLZ Turbo 140 410 -27 1.0 n/a
Quaker State 156 410 -30 0.9 n/a
Red Line 139 475 -40 n/a n/a
Shell Fire and Ice 155 410 -35 0.9 0.12
Shell Super 2000 155 410 -35 1.0 0.13
Shell Truck Guard 155 405 -35 1.0 0.15
Spectro Golden M.G. 175 405 -40 n/a n/a
Unocal Super 153 428 -33 0.92 0.12
Valvoline All Climate 130 410 -26 1.0 0.11
Valvoline Turbo 135 410 -26 0.99 0.13
Valvoline Race 130 410 -26 1.2 0.20
Valvoline Synthetic 140 450 -40 1.5 0.12
5W-30
AMSOIL 168 480 -76 0.5 n/a
Castrol GTX 156 400 -35 0.80 0.12
Chevron Supreme 202 354 -46 0.96 0.11
Chevron Supreme Synt. 165 446 -72 1.1 0.12
Exxon Superflow HP 148 392 -22 0.70 0.11
Havoline Formula 3 158 420 -40 1.0 n/a
Mobil 1 165 445 -65 n/a n/a
Mystic JT8 161 390 -25 0.95 0.1
Quaker State 165 405 -35 0.9 n/a
Red Line 151 455 -49 n/a n/a
Shell Fire and Ice 167 405 -35 0.9 0.12
Unocal 151 414 -33 0.81 0.12
Valvoline All Climate 135 405 -40 1.0 0.11
Valvoline Turbo 158 405 -40 0.99 0.13
Valvoline Synthetic 160 435 -40 <1.5 0.12
5W-50
Castrol Syntec 180 437 -45 1.2 0.10
Quaker State Synquest 173 457 -76 n/a n/a
Pennzoil Performax 176 n/a -69 n/a n/a
A Quick Reference Guide to Oil Choices
Engine Oil Outside Temperature (*F)
SAE Viscosity -20 0 20 40 60 80 100
20W-20 no no yes yes yes yes yes
20W-40 no no yes yes yes yes yes
20W-50 no no yes yes yes yes yes
10W-30 no yes yes yes yes yes yes
10W-40 no yes yes yes yes yes yes
10W no yes yes yes yes no no
5W-30 yes yes yes yes yes no no
5W-20 yes yes no no no no no
A Quick Reference Guide to Oil Choices
Engine Oil Outside Temperature (*F)
SAE Viscosity -20 0 20 40 60 80 100
20W-20 no no yes yes yes yes yes
20W-40 no no yes yes yes yes yes
20W-50 no no yes yes yes yes yes
10W-30 no yes yes yes yes yes yes
10W-40 no yes yes yes yes yes yes
10W no yes yes yes yes no no
5W-30 yes yes yes yes yes no no
5W-20 yes yes no no no no no

All of the oils above meet current SG/CD ratings and all vehicle manufacture's warranty requirements in the proper viscosity. All are "good enough", but those with the better numbers are icing on the cake.

The synthetics offer the only truly significant differences, due to their superior high temperature oxidation resistance, high film strength, very low tendency to form deposits, stable viscosity base, and low temperature flow characteristics. Synthetics are superior lubricants compared to traditional petroleum oils. You will have to decide if their high cost is justified in your application.

The extended oil drain intervals given by the vehicle manufacturers (typically 7500 miles) and synthetic oil companies (up to 25,000 miles) are for what is called normal service. Normal service is defined as the engine at normal operating temperature, at highway speeds, and in a dust free environment. Stop and go, city driving, trips of less than 10 miles, or extreme heat or cold puts the oil change interval into the severe service category, which is 3000 miles for most vehicles. Synthetics can be run two to three times the mileage of petroleum oils with no problems. They do not react to combustion and combustion by-products to the extent that the dead dinosaur juice does. The longer drain intervals possible help take the bite out of the higher cost of the synthetics. If your car or bike is still under warranty you will have to stick to the recommended drain intervals. These are set for petroleum oils and the manufacturers make no official allowance for the use of synthetics.

Oil additives should not be used. The oil companies have gone to great lengths to develop an additive package that meets the vehicle's requirements. Some of these additives are synergistic, that is the effect of two additives together is greater than the effect of each acting separately. If you add anything to the oil you may upset this balance and prevent the oil from performing to specification.

The numbers above are not, by any means, all there is to determining what makes a top quality oil. The exact base stock used, the type, quality, and quantity of additives used are very important. The given data combined with the manufacturer's claims, your personal experience, and the reputation of the oil among others who use it should help you make an informed choice.