so- your longtime mechanic is smarter than the car manufacturers and oil companys and u believed him?! excess detergents on an old engine usually spell trouble as u r stirring up old sludge etc which isnt a good idea.. wes

 

go with proper oil designed for cars and add a bottle of zddp additive for piece of mind, don't believe myths and tails, I've heard other putting diesel oil so im not surprised, but don't experiment on your car, replace the oil asap.

 

i know a few that use diesel oil in their gas engine no problem. it does cost more. 1 gallon of non synthetic valvoline 15-40w diesel oil cost me 14.99 + tax. 4 qts non synthetic valvoline 10w30 racing oil cost me $10.00 + tax.

 

Okay guys thanks. I only have about 30 miles or so on it since the oil change with no real hard driving. So with some luck, no harm has been done.

 

Diesel oil has extra additives to deal with sulfur contamination and to keep soot particles suspended. Neither of which you have any use for in a gasoline car. In general it will work OK, but why?

 

Mmmmm... Generally knocking isn't good. Does it go away after the engine warms up or is it constant?

 

Weird. I'd drain it and start over. Go with the ZDDP additive if you want more additives in the oil, but I don't think it's real nessessary.

 

most "diesel" oil is also rated for gasoline engines.

 

This is correct. in my shop we use the same oil in the diesel engines as we do in the gas engines.

 

you could remove the oil filter and look for signs of sludge or contamination. I've also seen filters do some stange things.

 

I use rotella 15w40, (Diesel) oil as well with out a catch. If u think it's the oil u used then change it back. But it mabey your oil filter? Do you have a oil pres. gauge or a idiot light?

 

Oil pressure seems to be fine. All I have for measuring is the original gauge. But it reads normal. The sound is intermittent and does not always occur. My first thought was maybe that I need to adjust the valves. The sound sounds high on the engine, not like a main bearing or rod clank.

The whole thing started after I changed the oil.

What difference does the oil filter make?

 

Does your motor have a oil filter by pass valve in it? Rocker arm's are most generally the last thing to get oil in the motor, if there is no oil filter by pass valve then a pluged up oil filter will starve your motor of oil.

 

Don't drive it. Change oil and filter back to your usual ASAP. You may need to touch up your lifters. A knock is usually a deeper sound at the bottom of the engine. A higher pitched "clatter" usually indicates lifters and is at the head level. A big screwdriver to your ear will act as a stethoscope. Cut open the filter to see what the media caught. Good luck. You're probably fine.

 

Just like most oil threads. Some going "AHHhhhh.... take it out ASAP". Others say, "don't sweat it we do it all the time". Oil's a goofy thing, it's difficult to be sure what to believe.

 

And some say both. When in dought, Ask your we-je board. Give us your 2 cent's CandyAppleRed

 

I really don't see how changing to 15W-40 will cause a knocking sound. If anything he should get better oil pressure.

Now I could see switching from 15W-40 to 0W-20 causing the valves to clatter.

 

CRAP. This is NOT GOOD. Changed the oil and filter. Started right up, and no noise at all. Ran her for 5 minutes in the driveway and nothing.

Then I took her out. After another few minutes, there is was again. A knock, knock, knock at idle. Either I cannot hear it or the sound goes away at speed. Took her home and crawled underneath. The sound is clearly from down there. I have no idea what it might be, but it's no lifter. I have a hard time believing that this might be a bearing or rod. I don't drive her hard at all. Before I changed the oil I had no issue. I've never seen any blue smoke or seen a drop in oil pressure. The needle drops off when she's not running and jumps right up to the little mark just to the left of the H on the dash gauge.

Anyone know what might be going on here?:shrug:

 

Pick up might be clogged with debris after it runs awhile starving the motor. You know what youll have to do. Can you get the pan off in the car? Check the pickup and for loose, blue caps.

 

What good would that do? I have solid oil pressure. If the pickup was clogged the pressure would suffer right?

What blue caps?

 

rod or main bearing caps that are blue from heat

 

Wouldn't I see remnants in the oil when I changed it? Or would they be too large to pass thru the drain hole?

 

Your symptom point to excessive bearing clearances somewhere.
They are not horribly loose because you have no sounds when engine is cold and clearances are tight and oil is thick.

At operating temp the oil is thinner and clearances are larger and you have noise.

How long since this engine was rebuilt?

Engine sludge can hold clearances close and then the detergents in the diesel oil washes the sludge out and noise starts.

 

I have no idea how old the engine is. So the detergents may have caused this? Oh this sucks....

 

try a straight weight weight oil > sae 30 (not 10w30).

 

I just went from diesel oil, to 10W30 and now SAE 30? Sounds more like I need to add the damn sludge back in....

Sorry, I'm ranting. My dream car now sits still after driving it a total of 300 miles.:thumbsdown:

 

your bearing knock could very well have no relationship to your recent oil change.

Z.

 

i forgot all about that fact that some people have put straight STP in and engine(i saw the stp done) 90w gear oil , saw dust , etc. to quiet a knock. yep a freind had a 70 something dodge challenger 318 and it burned oil and had a knock and he put straight 50w and bought a bunch of stp and kept adding stp and it eventually blode up good ! blode up real good and busted the block, and he had a 440 to put back in it. i heard of all sorts of stuff being done to keep and ingine quiet till the car was sold. could be thats the case with the car you have, heavy weight oil put in to hide a knocking rod. not everyone that sells a car including a mustang owner is honest. a friend has ben taken twice by private sellers. he bought a 302 cougar that was a lie and a mustang that has a wore out engine but was pulled and painted and sold as a rebuilt engine. his boss paid almost 15,000.00 for a 70 charger painted general lee off ebay and what was delivered was a rusted out brush painted body with a worn out/water in the oil pile of junk.

 

My brother bought a 65 Conv. Ran Riselone engine cleaner in the engine then after changing the oil the same thing...a lower engine knock. We dropped the oil pan and discovered a rod bearing was the culprit. We took the crank out with the engine in the car took it to the machine shop, had it worked on and with new rod and main bearings put it back in the car without having to pull the engine. He was going to buy a crank kit but this turned out to be cheaper. While we were at it replaced the oil pump. A crank kit for a 289 with rod and main bearings cost around $200.

 

If you've got a bad bearing (and it sounds likely), I'd be very surprised if it's due to anything that you did.

Not the end of the world, certainly better than most of the other potential surprises lurking in a new-to-you vintage car. I'm certain there are plenty of folks here who would happily trade your bearing knock for a leaky cowl...