Oil weight question

[33 IMP]

I would have recommended 20/50 conventional, for an old race engine, till I read 55 lbs at idle.
Now suggest 10/40, but 10/30 should be okay too .
Sound like clearances are pretty tight for an ex-race engine.
Look for conventional oil with zinc in it.

 

[Cranky]

Baby Blue ran Castrol GTX 20-50 during that period as well, and my friend Bob, who sold me the car in 1983, raced it on a regular basis. I can't speak for the bearing condition, as the engine has never been apart, had 119,000 when I sold the car in 2021, and still ran great. I switched to Rotella 15-40 when I owned the car the second time, then went to Valvolene VR1 20-50, after Shell cut the zinc content in Rotella, with the advent of DEF systems in the big trucks.

In the late 70s, I ran Quaker State 10-40 in my daily driver GTX. I've heard that oil was pure junk, and it sludged my dad's cars, but I got away with it, probably because of frequent oil change intervals. I needed the 10W viscosity for cold starts back in the day, not an issue with the current one. As stated in one of the earlier posts, driving to Carlisle in 100 degree heat is a different situation.

My first clue was when I did an intake swap on a 289 in my 66 Mustang FB back around 77. In all the little pockets in the lifter valley was this silvery sediment like material. Dabbed my index finger into one and rubbed it between my thumb and found it to be pretty slimy but at the time I thought it was just something in the oil itself. The centrifugal filter on my bike showed the same. It wasn't until the mid 80's when I tore down a 360 that was in my pickup and found the same thing in the lifter valley but the majority of the babbitt material was gone from all the crank bearings to the point you could see the copper. The crankshaft was perfect though and the engine was VERY clean.

 

[Black_Sheep]

I’ve run straight HD 30w in the GTX for more years than I can remember. My decision is based on the recommendation found in the Direct Connection performance bulletin. When zinc was reduced in the oil formulation I started adding a bottle of Lucas break in additive at every oil change. It became harder and harder to find 30w locally so now I order PennGrade from Summit and skip the Lucas additive. While others may disagree, I’ll stick with what works for me…

Good oil pressure, minimal oil consumption and the inside of the engine is clean as whistle.

 

[RemCharger]

My first clue was when I did an intake swap on a 289 in my 66 Mustang FB back around 77. In all the little pockets in the lifter valley was this silvery sediment like material. Dabbed my index finger into one and rubbed it between my thumb and found it to be pretty slimy but at the time I thought it was just something in the oil itself. The centrifugal filter on my bike showed the same. It wasn't until the mid 80's when I tore down a 360 that was in my pickup and found the same thing in the lifter valley but the majority of the babbitt material was gone from all the crank bearings to the point you could see the copper. The crankshaft was perfect though and the engine was VERY clean.

I always thought that was lead deposits from the good Ole gas.

 

[Cranky]

I would have recommended 20/50 conventional, for an old race engine, till I read 55 lbs at idle.
Now suggest 10/40, but 10/30 should be okay too .
Sound like clearances are pretty tight for an ex-race engine.
Look for conventional oil with zinc in it.

Used to run 20-50 in my street stuff because of the heat here in the summertime.....and well, still do since I still have a lot of it. Just no more Castrol GTX stuff.

 

[davescuda]

Right from the owners manual

 

[Bird 426]

Yes, I always thought that it was lead from leaded fuel too. My '72 Dart had the orginal engine when I went through it. It had a lot of deposit, intake valley and cyl heads. The gas tank insides were clean as a whistle from the lead, but I already had a stainless tank for it. My airplane engine always had lead deposits in it from leaded av gas. Not thinking bearing material.

 

[33 IMP]

Used to run 20-50 in my street stuff because of the heat here in the summertime.....and well, still do since I still have a lot of it. Just no more Castrol GTX stuff.

I run a witches brew of whatever is in the garage, but it's probably thicker than 20-50.
And it's hot in california too, and even hotter here.
(Witches brew: mostly 10-40 diesel, a couple quarts of high zinc straight 50wt racing oil 【was a gift, gotta figure out some way to use it, lol】 and a half bottle of zinc additive the first time, to break in a .557 solid.)
11 qt oil change for the 440. 15 qt for one of the diesels.

 

[s/w theo]

I would have recommended 20/50 conventional, for an old race engine, till I read 55 lbs at idle.
Now suggest 10/40, but 10/30 should be okay too .
Sound like clearances are pretty tight for an ex-race engine.
Look for conventional oil with zinc in it.

I did the oil change & used conventional 10w-40 & a Hasting's filter. It was not a dedicated race car, it was driven on the street a lot. First owner, who I got it from, would drive it to Englishtown Raceway, run it, then drive it home. Probably 20 miles or so each way. No slouch but not temperamental either. It does sound pretty awesome though.

 

[s/w theo]

Watch Lake Speed Jr's YouTube channel on oils. Very informative. For your buddies RR I'd use conventional 10W40.

I did watch that video the other day. Lot's of good info. Thanks