Corvette C3: How to Check Engine Oil Level

I'm pretty sure it was my dad who taught me years ago, to always check the engine oil level with a cold engine. That way, most of the motor oil would be in the oil pan. And to always do the checking with the car sitting on a level surface.

It made sense and that's what I've always done. Well, until the early 1980s when I purchased a '76 Corvette Stingray.

For one reason or another, I was looking through the owner's manual and read the Engine Oil and Filter Recommendations section. And under the Checking Engine Oil Level paragraph, it read:
The best time to check it [oil level] is as the last step in a fuel stop. This will allow the oil accumulation in the engine to drain back in the crankcase.
From that point on, I started checking the engine oil level when the engine was warm.

But I guess it really doesn't matter whether you do the checking with a cold or warm engine, as long as you allow for most the motor oil to drain back down into the oil pan if you're checking a warm engine. Any residual oil remaining in areas other than the pan would make little if any difference.

What really matters is maintaining the right level of motor oil. Actually, there is a range for determining that, as well as the recommended oil type and viscosity.

In order to properly check engine oil level simply remove the dipstick and wipe it clean with a rag or paper towel. Your T-shirt is an option, but it may get you in trouble.

Reinsert the clean dipstick all the way, then remove it again to get an accurate reading.

As the photo above shows, the dipstick is marked ADD 1 QT. and FULL, with the in-between area being the "safe zone." And just as you don't want your engine starved for oil, you also don't want to overfill it.

So what type of motor oil is the right one for my C3 Corvette? And what weight?


API, S, SE, SAE are some of the initials you'll come across when researching motor oils. It is likely that your car owner's manual will contain obsolete information on the subject, which is not surprising since we're talking about vehicles manufactured over 40 years ago.

The American Petroleum Institute, or API, provides engine oil classification, and if you read the 1976 Corvette Owner's Manual, you'll see that Chevrolet recommends the use of SE-rated engine oils, only.

API data states that SE oils are "Not suitable for use in gasoline-powered automobile engines built after 1979." But along with that very statement, the Institue also says that the SE rating was deemed obsolete as of 2010.

In other words, you will not find gasoline engine SE-rated motor oils unless you happen to find a batch of new-old-stock somewhere.

As a side note, the letter "S" on the classification indicates that the oil is formulated for gasoline engines.

But why the need for obsolescence?


As chemists make new discoveries, old oils are phased out. I think that's a good thing, and I also believe most current motor oils will substitute the old SE rating just fine, as long as they are formulated for older engines. But if you are unsure or unclear as to which grade to get for your vehicle, do some research online.

It's been my experience that—although well-meaning—most of the folks behind the counter at the local auto parts store know little if anything about cars in general. Especially classic cars.

A couple of months ago I lucked out at the local AutoZone store since they were closing out some of their STP oil inventory, and I purchased three 5-quart jugs of STP 10W-30 ($10 each) with the SN service designation as shown on the API "donut."

According to the API, oils categorized as SN were "Introduced in October 2010 for 2011 and older vehicles, designed to provide improved high- temperature deposit protection for pistons, more stringent sludge control, and seal compatibility."

Other current motor oils available—as of this writing—that would be suitable for older engines include SJ, SL, and SM oils.

And if you are curious as to what SAE means, those initials stand for Society of Automotive Engineers, the folks responsible for creating a grading system to designate the viscosity level of single-grade and multigrade motor oils, among other things.

And speaking of motor oil viscosity levels, a conversation topic that usually comes up during opera intermissions...

The "W" stands for Winter, a subject that we Floridians are not qualified to elaborate on, so that's all I have to say about that.

The 1976 Corvette owner's manual also states:
Non-detergent 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 Chevrolet engine.
From a bit of research I did, I learned that non-detergent oils were used before oil filters became standard equipment. I guess contaminants would get stuck to the insides of the engine which kept them from damaging bearings. Interesting.


According to a Wikipedia article, "Nearly all commercial motor oils contain additives, whether the oils are synthetic or petroleum-based." So do we need to add additional compounds to off-the-shelf motor oil?

And, if an engine is smoking badly, shaking and knocking like something evil is trapped inside, do you really think that an additive is going to fix that?

As far as oil (and gasoline) additives and that sort of thing go, I've used many in the past and have no real proof if they are beneficial or detrimental to an engine's health. But it seems to me they are nothing more than clever marketing flimflam intended to sell you stuff your car does not really need.

I do subscribe to the "an ounce of prevention is worth a pound of cure" saying, so I regularly check the motor oil level and change the oil and filter on my Corvette every 2,500 to 3,000 miles. It is easy to do and a must, IMO.

But if you're curious, along with 89-octane gasoline, my Stingray drinks full-synthetic, high-mileage 10W-30 motor oil.

Thank you for following my '76 Corvette Blog!

Product Links...  (#sponsored)

• 1976 Corvette Owner's Manual
• Majic Engine Oil, Gasoline, etc. Funnel with Flexible Extension
• Lumax 15 Quart Drain Pan and Waste Oil Storage
• ACDelco PF25 (Professional) Engine Oil Filter
• 1970-1982 Corvette Oil Filter (PF25) Correct Red, White, Blue

Royal Purple SAE 10W-30 High-Performance Synthetic Motor Oil | (5 qt.)