I don't know the history of the engine. I've had the car for 4-1/4 years and it has always run well up to now.
As for oil, I have been using Delo 400 with 1-1/2 oz. of Lucas Engine Break-in Oil Additive for additional protection. I guess it didn't work!
Sorry to hear you may have a ft cam gone bad.
Since you dont know your motors prior history maybe someone didnt do best breakin asnd or used oil with low zddp so when you got motor there was alrerady significant cam/lifter wear leading to poss bad lobe-s that no oil/oil additive can fix once that starts.
Also,as i have been posting here in team chevelle for yrs now the the delo oil was just a stopgap oil for stocvk to mild RV type cams when there was almost no oil with proper zddp lvls for ft cams avail .
The delo CJ rated oil is only good for stock to very mild perf cams so if anyone uses the delo oil with moderate to hot perf cams it doesnt reaslly offer enough zddp protection.
So the delo was better then nothing when it came to zddp protection for ft cams but
wasnt best case either,esp for aftermarket perf cams with higher then stock valve spring rates.
The weak 1.5oz lucas breakin lube with 5qts oil ratio didnt offer much additonal zddp protection either unless you meant 1.5oz of the lucas TB Zin ft cam breakin lube per qt oil?
And hopefully you didnt mean the Lucas oil stabilizer which some people mistake fo rLucas TB Zinc breakin lube with elevated zddp lvls for perf ft cams.
So when you were running a zddp lvl thats margianl for your perf cam it lasted 4.5-5yrs before maybe going bad which makes sence if you truely have a bad cam.
Shells rotella has even less zddp protection for ft perf cams in the newer since 1/2007 CJ rating which i haver also been posting for yrs now.
So there is no reason at all to not run an oil with proper zddp lvl for ft perf cams these days to properly protect them.
As for cam rec,if you find cam is bad i would rec the cam i am running in my mild 396 running approx 9.7-9.8 compression with a tweaked q-jet/stock intake/exh manifolds/331's/m20.
Stock GM L34 396/350hp hyd ft cam is 214/218 deg dur @.05,.461"/.480" gross lift,114 or is it 115 deg LSA and the cam i am running in my mild 396 is also a hyd ft perf cam with 222/226,.525"/.525" gross liuft,112 deg LSA.
That cam idles well-smooth (14.0-14.5") but has an authoritative sound letting you know it's not a stock cam,it's been in the motor approx 10yrs/8k miles.
That cam run well with 19-20 deg base timing + 18 deg mech in dist for 37-38 deg total by 2500-2600rpm + 12 deg vac adv for 50 deg timing at cruise.
That cam has a lot more umph then the stock gm had giving the car a lot more go/power feeling in the old BUTTOMETER,thats for sure.
A cam in that approx range would be a decent choice for your motor-auto trans setup,could go with a few more deg int dur to 225-226 deg and still be ok with auto trans & 396 ci as long as you stay with 112 deg lsa or go to 114 deg lsa.