Don’t Panic, I’m a Mechanic: What Oil Should I Use for a Chevy 350?

In this edition, we tackle a fairly technical question submitted by a reader: what oil should they use for a Chevy 350 engine?

For newbie car owners, you might be wondering why the right motor oil matters. Well, engine oil is the lifeblood of your engine, which is why you should always choose the best quality oil you can. Engine oil not only provides essential lubrication, it also prevents corrosion, cleans, and aids cooling, all of which improve and can even expand the life of your engine.

But first, let’s clear up a few things.

What is a Chevy 350?

If you’re wondering what a Chevy 350 is, it’s a type of small-block V8 engines produced by Chevrolet (under General Motors) from 1954 to 2003. It uses the same basic engine block that other Chevy cars use, albeit with a few key differences.

The Chevy 350 is called a small-block engine because, compared to its other Chevy engine cousins, it’s relatively smaller at 262 cubic inches to 400 cubic inches of displacement, or 4.3L to 6.6L engines respectively. There were several V8 engines produced in that period, from the Oldsmobile, Holden, Buick, Pontiac and Cadillac all using their own V8 variant, it was the Chevy 305 (5.0L) and the Chevy 350 (5.7L) that became the Chevrolet/GM standard.

The Chevrolet small-block engine is a series of V8 automobile engines used in normal production by the Chevrolet Division of General Motors between 1954 and 2003, using the same basic engine block. Referred to as a “small-block” for its comparative size relative to the physically much larger big block Chevy, the family spanned from 262 cu in (4.3 L) to 400 cu in (6.6 L) in displacement.

As for the Chevy 350, its first appearance was in the 1967 Camaro as an L-48 high-performance option. The first Chevy 350 was 5.7L and had a 3.48in (or 88.39mm) stroke, although the exact displacement was actually 349.5cu.

By 1969, most of the cars in the Chevrolet catalog had an option to have a 350 engine installed.

Chevrolet Camaro Engine
Source: Wikimedia Commons

Why Do I Need Motor Oil?

For first-time car owners, the wide variety of motor oils available in the market may be a little intimidating, with some newbies asking, why do I even need motor oil?

Of course, even the most inexperienced car owners can answer that question: the oil makes things slippery, so the engine won’t break.

And that is correct, in the most basic sense, so let’s dive in a little further:

Motor oil serves more than its fair share of purposes in an engine. First, it acts as a lubricant. An internal combustion engine understandably has a large number of moving parts. For it to operate correctly, almost none of those metal parts should make contact with one another. This can be achieved by having a healthy dose of lubricant, which provides a thin film of oil as a barrier between the parts.

Beyond this, motor oil has other purposes, a secondary purpose is that it acts as a coolant for engine parts that are far from the water jacket. In some vehicles, like motorcycles, the transmission is oil-cooled.

Another purpose for motor oil is to catch the particulate matter than slips through the piston rings. Piston rings in general don’t create air-tight seals, which leads to combustion by-products like carbon particles to slip through the rings and into the piston chamber. Over time, these carbon particles harden and start damaging your engine. To prevent this, the motor oil traps these particles and suspends them, limiting the damage they can do, and carrying them into the oil filter.

Motor oil also neutralizes naturally-occurring acids in the engine. Sulfur that’s present in gasoline can react with water and oxygen, creating sulfuric acid, which is corrosive and very damaging to your engine. Many different types of motor oil have special ingredients in them that are added specifically to neutralize acids and keep your engine clean. Also added to motor oil are various types of solvent that helps your engine get rid of any built-up gunk like wax and tar.

Car Engine Oil Change
Source: Wikimedia Commons

What are the Different Types of Motor Oil?

There are various different kinds of oil out there, but they can be divided into three main categories: synthetic oil, mineral oil, and mixed oils. Mixed oils, also known as ‘part’ or ‘semi’, or sometimes to sound fancy, “synthetic technology,” is simply a mixture of mineral and synthetic oils (albeit of varying ratios).

The first type of oil, mineral oil, is created through a refinement process that involves fracking crude oil. This purifies the oil and separates unnecessary compounds and elements. In general, mineral oils are of lower quality than synthetic oil because of the wide variance in molecule size as compared to synthetic. This variance allows for a greater amount of friction, which, in turn, slows down the flow of oil in and around the engine.

Synthetic oils, on the other hand, are usually lab-processed, thus making their production more streamlined and easily controlled. As such, synthetic oils have much more consistent molecule sizes, which then allows for less friction and more flow of oil throughout the engine. Because the flow rate is high, the oil can circulate faster even at colder temperature, thus allowing for more protection against engine abrasion.

What Kind of Oil Does My Chevy 350 Need?

In general, late-model Chevy 350’s, like the LT-9, L83, L98, L05, or the L31, most people use 5W-30 oil. For older models, like the LT1, L82, or L81, most people use either 10W30 or 10W40.

What do those numbers and letters mean?

Well, the numbers represent the viscosity grade of the oil (based on the Society of Automotive Engineers j300 standard), and the W stands for winter. So a 5W30, for example, means that it has an SAE J300 viscosity grade of 5 during winter temperatures, and a viscosity grade of 30 in warmer temperatures. Same goes for 10W30/10W40.

These types of multi-grade oils are popular and widely used because of how versatile they are in different weather conditions. Unless your car experiences extreme weather conditions (which, in all honestly, probably won’t happen unless you drive your Camaro or Impala into the Arctic Circle or a volcano), the multi-grade oils will continue to flow and thicken appropriately.

Which Oil is Better for a Small Block Chevy?

So pour 5W-30 for LT-9, L83, L98, L05, or the L31 and for LT1, L82, or L81, use 10W30 or 10W40.

Of course, the type of oil your Chevy 350 uses is still fairly dependent on your living conditions: colder countries should get a lower viscosity grade oil and hotter countries should get one with higher grades.

In terms of lubrication, the 5W-30 is better than the 10W30. Both have similar SAE ratings, which is 30. So they will each perform well at high or operating temperatures.

In general, the 5W-30 is ideal for private vehicles, like a ’55 Chevrolet Corvette, and the 10W30 is more suitable for commercial vehicles.

Now that you’ve chosen your oil, make sure you have the proper accoutrements, namely an oil filter and an oil pump.

The oil pump is the part of the engine that circulates the oil in and around the engine parts, from the camshaft and the pistons, all the way to rotating bearings. The oil filter, on the other hand, stops debris and built-up gunk from being re-circulated into the engine.

It is vital that any dirt or contamination picked up by the circulating oil be removed before it is pumped back into the engine. Tiny dirt particles between 10 and 20 microns do much of the damage to bearings, cylinders and other moving engine parts by rubbing and causing wear.

For the Chevy 350, oil filters from brands like Delco and Fram are recommended because they carry the Society of American Engineers, or SAE, seal of approval. The Chevy 350 oil capacity is at 5 quarts, if it’s an unmodified stock model.

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