Cliff notes: AC Delco is garbage!

I cut open a Mobil 1 filter, Carquest, and AC-Delco. These all came off the small block on my vette or truck.

The Mobil 1 is a much deeper can which I like, due to the extra surface area. It's also a thicker can so it is less prone to puncture than the others.

The Mobil 1 had a silicone check valve in it. Not really needed on small block. Carquest had no check valve. AC-Delco has a rubber valve. I don't know what type of rubber, but the age and exposure to oil makes it stiff and not seal well.

The AC-Delco has paper ends on the filter media and the back end is open. What this means, is paper caps press against the metal spring and against the check valve, and any oil that forces past this goes unfiltered. These paper caps aren't glued on well at all either. Parts of it had already come loose, and the rest peeled off easily. Anywhere that glue fails oil will bypass the filter. The Mobil 1 and Carquest media was glued into metal caps. The back cap is closed off, so no chance of oil bypassing there. The glue on those was awesome, I had to cut the filter media to remove it.

The Delco had a plastic core. Oil filters flow from the outside in, so I guess it's possible that it would collapse easier if the filter was blocked up.

The filter media was pretty similar in length. The AC-Delco was about 10% shorter than the Carquest, and the Mobil 1 halfway in between. Don't pay attention to the width in that photo, I cut the Mobil 1 and Carquest about 1/2" short because they were glued so well to the endcaps.

The filter media itself was thicker on the Mobil 1 but seemed to be more porous. The AC-Delco was very thin and dense.

The Mobil 1 and Carquest also had pleats on the pleats. This doesn't really add to the surface area, so I assume the purpose is to keep the filter pleats seperated from each other so they don't block oil flow. The AC-Delco filter definitely had pleats that were smashed together. And with the engine running, the pressure difference on the filter would tend to press the pleats together also.




I also cut open a Fram and Fram Tough Guard filter removed from a Nissan. These were your typical 4cyl import filter, but they were basically similar to the AC-Delco with paper caps, except with far better glue and seemingly better filter media similar to the Carquest.

Also the Fram Tough Guard was exactly the same as the regular Fram except for a silicone check valve and a screen over the pressure relief. (The SBC filters tested above did not have a pressure relief, it's built into the oil pump.)

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Good stuff! Think I'll stick with the Mobil 1 or NAPA Gold filters.

good to know

Nice effort CC. Will that change the brand you use?

My thoughts:

Check valves, there are 2 kinds used in some filters, an anitdrainback (usually a flapper) and the check valve which is a bypass valve but can also be an ADB. The check valve will bypass the filter when cold, very dirty or internally broken (unusual). As CC said some filters don't have them. The pressure relief in the pump keeps oil pressure within specs on cold startup and when there's blockage (like in the filter).

I like CC's observations from a design standpoint (wish I could have been there for the inspection).

I have to say though, for many years, I went thru hundreds of AC Delco and Frams on SBCs with no problems before I succombed to the internet and switched to M1 and K&N on the C4 and Silverado.
I think the Fram thing probably has been blown out of proportion by the internet but, if there's even a chance of internal failure, I don't want it to be in my motor.

I think filter media can make a difference but it's a small difference especially if you change frequently.

I ran a SBC in my truck to 250,000 using Frams with 3,500 intervals. It didn't start to smoke until 230,000. So, I'm satisfied with that.

Do a Wix. Everybody swears they're the best...let's see for real!

I have a small wix filter but its from my motorcycle. I'll see if it cross references to anything else or if its apples and oranges.

car quest has a rebadged version of a wix.. don't really buy carquest stuff so i dont' know which is which.. napa golds are wix IIRC

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Of course. I had assumed Delco was good enough, and avoided Fram (which is why I didn't have a SBC one to cut open.)

Now I'll avoid both.

Doesn't AC Delco make an AC Delco Gold? I wonder if it's better?

After seeing all the data against Fram, I researched filters for some time, and Puraltor One and WIX (Napa Golds) just seem to always be regarded as well engineered fitlers, so I stick with them on all my vehicles now.

Thanks for taking the time and effort to do this. If you ever get a chance, do this to a K+N oil filter and give us the review. I use K+N when I can, and Mobil 1 if I can't find the K+N when I'm due for an oil change. I notice no difference between the two as far as oil pressure or anything.