Oil for my 496 BBC

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Dec 17, 2022
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I’m trying to figure out a good oil for my 496 full roller engine. It uses about a quart every 150 miles, (think it has low tension rings) so I try not to use an expensive brand, currently using Walmart diesel 15w40. I also like to use this viscosity because oil pressure is very low, around 10 to 12psi at hot idle.

I’ve read elsewhere that this is a good oil to use but I’m concerned about the so called anti-foaming and high detergent properties of diesel oil. Are they bad for my engine? If so, what should I be using?
Thanks!
 
I don't know what type of rings you have--super loosey goosey drag race rings?, but I have seen people build engines with low tension rings and use a vacuum pump--convert an emissions pump to overcome the issue. It was known it'd be an issue before the engine was built when using such rings in the day.

You should do a leak down test. You're probably needlessly losing a bunch of power and using more fuel.

I don't think the oil matters as much as some might think being it's a full roller engine and not having crazy flat tappets sliding on cam lobes with high valve spring pressure.
 
A quart every 150 miles is indicative of a serious mechanical issue, i would fix it.

If its indeed a full roller it does not have any particularly strenuous requirements walmart diesel 15/40 is likely fine.
 
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A quart every 150 miles????
Typo? Did you mean every 1500?

If it's really using a quart every 150 miles, that engine is done, time to look for another engine...

Race engines are often built "loose" and often times are built without valve stem seals but even then and with low tension rings that is downright ridiculous, how does it not foul the plugs burning that much oil?
 
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If it’s really sucking a quart every 150 miles it doesn’t matter. Use the cheapest 50 weight and keep the spark plug socket handy. It’s going to foul plugs. You can “fog” mosquitoes with it I’m sure.
 
If your engine is using a quart of oil every 150 miles then it’s done for. No oil is going to fix that.

The engine needs to be fixed.
Maybe you guys can help me with this. Plugs aren’t fouling, appear to be burning clean. Have about 4000 miles on them. No oil burning smoke, seems to have good power. Compression test runs 140 to 152.
 
Is this motor a 8.1/496 factory motor or a 454 stroker motor that is now a 489/496?

I had one of the first 502 GM Performance motors down the line and it was built with low tension rings, along with some seriously loose pistons because they figured (wrong) on expansion. It used a quart every 400 miles. Like yours, didn't blow blue smoke and didn't foul plugs.
Bottom line, it was built wrong and needs to come apart.
 
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Maybe you guys can help me with this. Plugs aren’t fouling, appear to be burning clean. Have about 4000 miles on them. No oil burning smoke, seems to have good power. Compression test runs 140 to 152.

There are only a few options for where oil goes.

It leaks
It burns
it it turns tvapor and is vented somehow.

Whether 140-152 is reasonable compression or not depends on camshaft (Cranking compression/DCR)
 
Is this motor a 8.1/496 factory motor or a 454 stroker motor that is now a 489/496?

I had one of the first 502 GM Performance motors down the line and it was built with low tension rings, along with some seriously small pistons because they figured (wrong) on expansion. It used a quart every 400 miles. Like yours, didn't blow blue smoke and didn't foul plugs.
Bottom line, it was built wrong and needs to come apart.
Not necessarily, I’m satisfied with the performance and I can buy a lot of oil for what a rebuild cost will be. Still would like to know where the oil is going. Will a leak down test tell me?
 
It’s a 454 stroker motor with a Scat crank, Eagle rods with SRP pistons and Bowtie rectangular port aluminum heads.
 
Probably. It might tell you where it isn't going too...

Who built this motor and how long ago?
I bought this car about 5 years ago. Car underwent a full restoration and engine was built by a machine shop in Beaumont, Tx. approx. 2002. Has good power, scary to get fully on it, at least to an old man like me.
 
Low tension rings (by themselves) won't cause a quart of oil consumption every 150 miles. Something is wrong. Give us some more information about the engine. I'd rather find the cause of your oil vanishing problem than recommend you an oil.

How long ago was it built and how many miles on it since the build?
How is it typically used? (low rpm cruise, stop and go city traffic, drag racing, towing, garage ornament, etc...)
What temp thermostat are you using and what's the typical operating temp?
What's your static and dynamic compression?
Rod and main bearing clearance?
What camshaft exactly?
What oil pump?

Perhaps most importantly... how was the break-in done?

I've seen this once before with a .030" over 454 BBC (460ci) where the "builder" put cheap slugs in it that were .020" shorter than stock and with a -12cc dish. (may have been -15cc, not sure) They were .040-.045" in the hole with a .040" gasket and the typical massive 119 cc combustion chambers of smog era BBC iron heads. The static compression was in the toilet at barely >7:1. To make matters worse, it had a rather hefty cam in it that was ~235-240 @ .050" with a DCR down ~5.5:1. This engine didn't want to idle below 1000 rpm and was an unresponsive turd. He had a similar issue with oil disappearing though it was every 300-400 miles, not 150. When the oil pan was pulled to start investigating, you couldn't see the pistons in the bores due to a black tar (sludge) coating the bottom of the pistons. It was bad enough that you had to scrape it out of the way to see the lock rings on the pins. Running the DCR so low and lugging it caused very high piston temperatures which coked the cheap oil he was using. Same as you, no blue smoke, no oil on the plugs, no external leaks, etc... it was all evaporating and coking around the pistons and cylinder walls. As you probably imagine, this engine had a bad overheating problem as well.
 
Not necessarily, I’m satisfied with the performance and I can buy a lot of oil for what a rebuild cost will be. Still would like to know where the oil is going. Will a leak down test tell me?
I get your point, I added a lot of oil to mine too. I put over 20,000 miles on mine before I got tired of adding oil almost daily. I'll bet the oil is going out the exhaust like mine did. It wouldn't fog but there were times when I had cars behind me at night I could finally see it coming out the pipes. I had buddies follow me who swore nothing was coming out.
You have a pcv on yours?
 
1) What is the current setup for crankcase scavenging?

2) What is the hot oil pressure at 3000 rpm?

3) Is it a deep pan with good windage control?

4) You are not over topping up the oil?

So far in this thread we have an engine with no car. Chevelle? Impala?
What is the car, trans, gearing?

I would chat with the engine builder if he is still kicking around.

Once you get the oil eating figured out, I would run Mercury I/O 25W40 marine oil in that - not diesel junk
 
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So an 8.1 vortec. Also why is it consuming so much. Do you have blowby when you take the cap off. Have you compression tested it. Has it had regular oil changes or a good flush and the pcv valve? Have you also tried replacing the intake manifold bolts which is a fix gm issued for the 8.1.
 
Here's a post i found but you should research on your own as you know those issues better than us.

 
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