Oil weight

I have an 1982 Chevy caprice and I’ve been using 5w30 oil, should I be using something else maybe heavier? I live in Phoenix Arizona btw. Thanks for any help.

Why do you want to switch?

I was told old engines like mine use thicker oil. I’m not really sure though.

No. You don’t need a heavier oil.

The 5W-30 oil means when the engine is started cold the oil has the winter viscosity of a 5 weight oil. That’s what the 5W indicates This ensures that the engine components get lubricated as soon as possible when the engine is started cold. Even at 90 degrees. Once the oil comes in contact with hot engine components such as the bearings, it converts over to a 30 weight oil to put a film between the bearing surfaces to prevent wear.

If you switch to a heavier oil, it will take longer for the oil to get to engine components when the engine is started cold. And when the oil comes in contact with hot engine components it can become so thick where it spends too much residence time on those hot components causing the oil to become oxidized at a faster rate. Which requires more frequent oil changes.


Thanks. I was told to use “Lucas” oil additive. I was thinking if my oil need an additive maybe I need new oil. I just think additives might be bad, any word on them?

Don’t add anything to the oil. Just use the 5W-30 oil recommended by the manufacturer.


5W-30 sounds too light for an older car in Phoenix where summer temps can be extremely hot. Use the weight that your owner’s manual specifies. If you never use full throttle acceleration, then 5W-30 might be ok in the summertime in Phoenix.

PS, I just recalled that I have the owner’s manual for my 1984 Chevrolet, only two years newer than 1982. It says that 5W-30 is ok to use if the outside temperature is not expected to exceed 100F prior to the next oil change. There is also a chart that says that 10W-30, 15W-40, 20W-20 and SAE 30 are ok above 100F. 5W-30 is ok to below -20F, 10W-30 is ok down to 0 degrees F, 15W-40 is ok down to +10F, 20W-20 is ok down to +20F and SAE 30 is ok down to +40F.

PSS, I also have my owner’s manual for my 1981 Chevrolet. It says that the preferred viscosity grade above 0 degrees F is SAE 10W-30. If cold weather starting problems are encountered below 0 degrees F, SAE 5W-30 viscosity oils may be required.

It also gets hot in Minnesota. We can see temperatures as high as 115 degrees for days in a row. But is that cause to switch over to a thicker oil?



If you need to add oil between oil changes, assuming 5K miles between changes, this is normal. If you need to add a quart every 2K miles this is normal. If you need to add oil every 500 miles perhaps you need a thicker oil. So, what is really going on with your car? A can of 5W-30 oil is pretty cheap (at Walmart) so exactly what is your concern?

Lucas and similar products have limited benefits and if your engine is running smooth and quiet and there is no oil burning problem there is no reason to add it. I would consider using 10W40 in Phoenix but if you have been using the 5W30 with no problems why change?

I just got the car and changed the oil first cause it was sitting for about a year. After I changed it the guy at the parts store tells me I should have used 10w-40 instead. Just asking because I’ve never owned anything older than a 1993.

Don’t listen to the person behind the parts counter. Listen to the owners manual.


5W-30 oil weight is best for getting the best mpg. See how it goes since this is a “new” car for you. Check the oil level every 1000K miles and add as needed. If you don’t add much oil then 5W-30 is OK for this car. If you need to add 2 to 3 quarts before your next 5K oil change, then try 10W-30 which should be fine in FL.

For the century that automobiles have been on the road, there are all kinds of myths about what kind of oil should be used. The owner’s manual is the key here. 5W-30 should be fine if that is what is recommended in the manual A cold start is a cold start, even if the temperature outdoors is 100 degrees F. 5W-30 flows better than 10W-40. If you are having no problems, stick with the 5W-30.

Back in the 1970s, a colleague bought a new 1976 Pontiac. When cold weather hit, the car wouldn’t turn over quickly enough to start. The service manager of the Pontiac dealer made the decion that multi-viscosity oil was no good and when the oil was changed at the dealership, 30 weight was installed. Naturally, at zero degrees, the car would have problems starting. When my colleague figured out what happened, he made the dealer’s service department replace the oil with the 10W-30 called for in the manual. He had no more starting problems.

My son now owns a 2006 Chevrolet Uplander that I sold to him about three years ago. The manual calls for 5W-30. His mechanic convinced him to use high mileage 5W-30 because the Uplander has 110,000 miles on it. The car did not leak or use oil, so I doubt that the high mileage oil is really doing any good, but it probably doesn’t hurt anything either. My son just pays for something he probably doesn’t need. I keep quiet, because it’s his business and he is really doing his best to make the Uplander last.

Additives usually aren’t needed, and some additives such as STP thicken the oil and may actually cause problems. Occasionally, when the hydraulic lifters made noise in my 1965 Rambler, I would pour in a small can of Wynn’s friction proofing which quieted the lifters. I haven’t found the need to use additives in any of the cars I’ve owned since the Rambler.

If I owned a 1983 Chevy in Phoenix I would use a 5W40 SYNTHETIC. This oil will give you the good flow qualities when cold and have very good film strength for driving at those hot summer temperatures. If you tow a trailer, the 5W40 would be especially usefull.

When your car was built, there was very little synthetic oil, so 5W30 normal mineral oil was the best compromise. I had a 1984 Impala and used 0W30 (then called “SynArtctic”) all year round since I live much further North near the Rocky Mountains, and we have very cold winters.

In any case, don’t use any additives, you don’t need them…

115 for days in a row in Minnesota? Ja sure, dot may be so but first we must check da temperature charts. Ole and Lena.

Ya! It’s not da heat! But da humidity! Ya!


I’m assuming you don’t have the owners manual. Maybe see if it is available on-line somewhere. A lot of owner’s manual for older cars have been posted on-line. Then follow the recommendations for the oil weight per the manual.

I concur with the comment from the auto parts guy that 5-30 weight may be too light for the way your car’s engine is designed. The 5 part. 10-30 I woulnd’t have much concern, but 5-30? For an early 80? I don’t think so. Not an emergency situation, but try to find what the manufacturer recommends for this make/model/year, and next time you change the oil, use that. Drive conservatively in the meantime. I think that’s the safest bet.

I’d probably use 10W-30 on an engine that old, especially in Phoenix’s climate.

@jaspn Use the oil additive, your camshaft will be happier and last longer. Oil no longer has the zinc and sulfur additives to properly lubricate sliding contact points in the engine. Your 82 has flat tappet lifters that slide on the cam surface not roller lifter used on modern cars. The Lucas oil additive, or STP or several others adds the zinc and sulfer. You also could use oil for modern diesels as that oil still has those additives (like Rotella T oil).