Reviving a 71 C10! Curious about suitable oils.

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Apr 9, 2024
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Rig:

1971 Chevy C10
250 I6
3 on the Tree
2wd
~75,000 miles(believed accurate/not rolled over!)

History: Bought new by my paternal grandfather, driven by my parents for a while. Feb of 1987, with 72k indicated, it was given to my aunt on my dad's side. They put ~1,500 miles on it between then and 2003, at which point they parked it in a garage because they simply didnt need it anymore. Jan of 24, they offer it to me as they are selling the property it was stored at, which I happily accepted. March, truck arrives, and within two weeks I have driven it a short distance.

Current status: Running, driveable, still being serviced.

Work performed so far: Oil change with Wix filter using Rotella T4 + ZDDP additive bottle, six new RJ45TS plugs, a new battery, and two front tires.

Planned work: A few more oil changes as the oil I put in it is cleaning so much sludge out of that engine it isnt even funny(as intended), full ignition service, fuel pump replacement, carb overhaul, all fluids changed, possibly a clutch depending on how adjusting it pans out. Oh, and of course a bunch of gaskets, as I'm sure that T4 will.be washing away piles of sludge that is keeping it sealed. Happily, straight sixes are easy to work on.

Oil sample: Oil in engine when the truck was received was sampled and is currently in Blackstone's labs to give me a baseline of internal wear and see what was in oils made decades ago. May switch to a different lab as Blackstone is excruciatingly slow; results still pending nearly two weeks after they began testing.

Planned use of vehicle: Daily driver 20k/yr.

Planned modifications: Air conditioning, FM radio.


Any recommendations for an oil that's as readily available and affordable as T4 but has the necessary zinc for my cam? Planning on going by lab results to determine change interval but I am suspecting ittl end up settling in on 5k miles. Engine is mechanically healthy from the signs I have just listening to it. Starts INSTANTLY, good power when the shot ignition system lets it hit on all six(and even when it doesnt it still pulls well!), good oil pressure. Lifters pumped up within 20-40 seconds of the first start.

I believe the speedo has NOT rolled over because there is so little wear and tear elsewhere in the truck(steering box tight, driveline perfect, no squeaks, rattles, etc) and because it still had G78-15 bias plies tangled around the front wheels with 4-5 32nds tread left. If it had enough miles on it to have rolled the ODO those would have worn out and been replaced YEARS ago, yanno? And the steering would be sloppy, shifting wonky, et al. 98% sure it genuinely only has 75,000 miles on it.

Here's some video of a short drive I did after getting the fuel tank working again!
 
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Literally, any 30 or 40 weight oil on the shelf will be great for this application so long as it has sufficient oil pressure. Today's oil is way better than what was available when it came out. Today's oil has enough anti-wear additives so that you will not need extra stuff. The cam is a low lift one with valve spring pressures that are low to match, so it is not especially taxing on the oil.

Nice truck, BTW!
 
Literally, any 30 or 40 weight oil on the shelf will be great for this application so long as it has sufficient oil pressure. Today's oil is way better than what was available when it came out. Today's oil has enough anti-wear additives so that you will not need extra stuff. The cam is a low lift one with valve spring pressures that are low to match, so it is not especially taxing on the oil.
I thought that about my 85 F150's 300 I6, too, but right around the time zinc additive levels dropped out of oil I lost 1,000rpm on the top end and it developed a weak hole practically overnight. I chalked that up to the cam getting hit hard by the lack of zinc in the oil. Then again that engine was already north of 350k miles at the time and needed 20w50 in the sump to keep the bottom end happy.

Currently, that 300 is due for overhaul. Got it to about 400k miles before 20w50 was not thick enough to keep the rods and mains happy. If I can I'll put roller lifters in it during overhaul.

Viscosity wise I will be using 10w30 or 10w40 in the Chevy as I will be driving it to work every single day winter or summer(I live in TN we don't get enough road salt to rot it out) and need the multivis particularly in colder months.

I am in 125% agreement that today's oils are far cleaner and resist viscosity breakdown, acidity, etc compared to what I drained out of it last month. Part of why I sampled that oil is just plain curiosity on that front. As long as my cam isnt in danger of wiping I am fully confident modern oils will have zero trouble getting this 250 to 400,000 miles as well. 👌
 
Any HDEO 10W-30 will work well in that rig.

Cool DD - please keep us updated on how it works out!
A member a while ago did the same thing with a low-mileage 1978 Ford Granada 250 I-6. Search the word Granada and you will find UOA’s and a thread on the adventure.
 
I thought that about my 85 F150's 300 I6, too, but right around the time zinc additive levels dropped out of oil I lost 1,000rpm on the top end and it developed a weak hole practically overnight. I chalked that up to the cam getting hit hard by the lack of zinc in the oil. Then again that engine was already north of 350k miles at the time and needed 20w50 in the sump to keep the bottom end happy.

Currently, that 300 is due for overhaul. Got it to about 400k miles before 20w50 was not thick enough to keep the rods and mains happy. If I can I'll put roller lifters in it during overhaul.

Viscosity wise I will be using 10w30 or 10w40 in the Chevy as I will be driving it to work every single day winter or summer(I live in TN we don't get enough road salt to rot it out) and need the multivis particularly in colder months.

I am in 125% agreement that today's oils are far cleaner and resist viscosity breakdown, acidity, etc compared to what I drained out of it last month. Part of why I sampled that oil is just plain curiosity on that front. As long as my cam isnt in danger of wiping I am fully confident modern oils will have zero trouble getting this 250 to 400,000 miles as well. 👌
Given that, what was your question again?
 
Any HDEO 10W-30 will work well in that rig.

Cool DD - please keep us updated on how it works out!
A member a while ago did the same thing with a low-mileage 1978 Ford Granada 250 I-6. Search the word Granada and you will find UOA’s and a thread on the adventure.
Will have a look! Will be plating it and giving it a full tuneup later this week so hopefully I should have it running on all six reliably.
Sounds like a perfect candidate for a diesel rated oil. Plenty of ZDDP, and adequate viscosity for an older engine.

Cool truck! I remember those well.
Was my thought reaching for T4 as well. Within the viscosity range, good detergent/dispersent package, meant for far more severe duty than driving a 3,500 pound stepside to work and hauling RC airplanes for play. 👌
Given that, what was your question again?
I want to make sure I use an oil that will extract a half million mile account of my engine under daily driving duties 20,000 miles a year on average. A 250 I6 should be able to do this, but it needs the correct oil changed at the correct frequency to do so.
At 350k your 300 may have simply lost compression due to worn rings or leaking valves. I wouldn't chalk it up to cam wear just because the zinc in the oil went down by 20%.
Rings/cylinders probably. I had to do a head gasket at 265k and the head was gone through by a professional machine shop at that time. decked 10 thou, 11 guides, 12 seals, ground and cleaned the valves, all good. I noted a LOT of ring ridge even then. Somehow it never burned any oil, but in the last couple years of service it had more exhaust coming out of the valve cover than the tailpipe on cold mornings.

It may be so worn out it needs sleeved, so it is entirely possible the rings just gave out. If I can get them out without breaking them I might try to measure ring gap but the ridge may be too severe to do so.
 
A good ACEA A3/B4 oil such as Mobil 1 or Castrol 0W-40 with Mercedes-Benz 229.5 approval will give more than adequate ZDDP and has high oxidation and deposit resistance, as well as many other desirable attributes. Such oils got me to nearly 500K on my old 1MZ-FE "sludge monster" engine.
 
Planned work: A few more oil changes as the oil I put in it is cleaning so much sludge out of that engine it isnt even funny(as intended), full ignition service, fuel pump replacement, carb overhaul, all fluids changed, possibly a clutch depending on how adjusting it pans out. Oh, and of course a bunch of gaskets, as I'm sure that T4 will.be washing away piles of sludge that is keeping it sealed. Happily, straight sixes are easy to work on.
I wouldn't be sure of that.
 
A good ACEA A3/B4 oil such as Mobil 1 or Castrol 0W-40 with Mercedes-Benz 229.5 approval will give more than adequate ZDDP and has high oxidation and deposit resistance, as well as many other desirable attributes. Such oils got me to nearly 500K on my old 1MZ-FE "sludge monster" engine.
Mmm maybe not a 0wXX in a US engine from 1971, but I will keep an eye out for those oils in a more suitable viscosity range.
I wouldn't be sure of that.
The fresh 5qts I put in it turned jet black and reek of sludge on the dipstick within the ~1hr of engine operation it has gotten since being put in there. Some of that may be residual from the previous change sitting in the front of the pan pulled into suspension as the truck was sitting nose down on flat tires at the time and I wasnt able to jack it up safely, but I dont think there was enough of it in there to account for such a rapid deterioration of the oil.

It will be getting a fresh change this weekend. I expect to have to do such rapid changes 3 or 4 times during the revival process.
 
Mmm maybe not a 0wXX in a US engine from 1971, but I will keep an eye out for those oils in a more suitable viscosity range.
You already said you wanted a 40-grade, that's what I recommended. Winter rating has nothing to do with it.

Those oils are some of the finest available anywhere with demanding approvals, and the price at Walmart is very good.
 
The fresh 5qts I put in it turned jet black and reek of sludge on the dipstick within the ~1hr of engine operation it has gotten since being put in there. Some of that may be residual from the previous change sitting in the front of the pan pulled into suspension as the truck was sitting nose down on flat tires at the time and I wasnt able to jack it up safely, but I dont think there was enough of it in there to account for such a rapid deterioration of the oil.
Deterioration?

"Cleaning" by an oil is mostly determined by the base stock composition. T4 is not a cleaning oil. Despite the name, oil detergents don't clean.
 
You already said you wanted a 40-grade, that's what I recommended. Winter rating has nothing to do with it.
This isnt a collector vehicle or a summer vehicle, it will be my daily driver all year around. That includes dark winter mornings when there's half an inch of ice to scrape off the windshield.
Deterioration?

"Cleaning" by an oil is mostly determined by the base stock composition. T4 is not a cleaning oil. Despite their name, oil detergents don't clean.
All I know is that oil picked up a LOT of crud in a hurry. It isn't gritty or sparkley, but as I already said, it turned jet black almost immediately and positively reeks of sludge. It's picking something up in there.
 
Had a 250/glide in my 66 Biscayne. Nice running motor.

You've got to, got to, put an HEI distributer in yours. I used an ebay Chinese whatever for $50 but you could go upmarket. Gapped my plugs wider (0.055?), might have picked up some power and MPG. Dunno because I got it dead, LOL. But it was a great running six. Mixed 87 and 93 to get the original 89 octane.

With the 3-speed you've probably got a range of running RPMs. I'd go with a 5w40 myself just so you get better lubrication when you're cold and winding up for the next gear.
 
Any modern oil will clean up loose sludge (the gloopy stuff) if you want to clean all of the baked deposits and varnish (ring lands) you need something better than normal oil.

Rotella 5w40 would work great in this truck.
 
Had a 250/glide in my 66 Biscayne. Nice running motor.

You've got to, got to, put an HEI distributer in yours. I used an ebay Chinese whatever for $50 but you could go upmarket. Gapped my plugs wider (0.055?), might have picked up some power and MPG. Dunno because I got it dead, LOL. But it was a great running six. Mixed 87 and 93 to get the original 89 octane.

With the 3-speed you've probably got a range of running RPMs. I'd go with a 5w40 myself just so you get better lubrication when you're cold and winding up for the next gear.
I'm hesitant to HEI it. I have seen 250s with HEI dizzies in them and it makes getting to #2 plug in particular a right pain. I plan on leaving it points fired if at all possible, but if my hand is forced...likely by the rumored low quality of today's points...I may go pertronix instead.

I will be turning somewhere around 2800-3200 on the freeway but I dont expect to be there on a cold engine. It's 5 miles of steady state country road driving between my house and my onramp and 7 miles of stop and go nashville traffic between work and that ramp. If it isn't up to full temp by then, oil and coolant, I have a stat to replace. Shifting up...no tach yet but prolly around 2k or so. 15 to 2nd, 30 into 3rd.

Eventually I may swap the rear gears for something in the 2.73-3.08 range. I dont plan on ever using this truck as a workhorse so I dont need the pulling power 3.73s give me.
Any modern oil will clean up loose sludge (the gloopy stuff) if you want to clean all of the baked deposits and varnish (ring lands) you need something better than normal oil.

Rotella 5w40 would work great in this truck.
I dont have any stuck ring issues. Never did. This thing was well looked after and well stored. It has excellent compression on all six pots, doesnt burn a drop of oil, starts INSTANTLY. Internal health seems perfect barring my oil sample showing wear metals in it....assuming Blackstone ever gets done testing it.

The gloopy stuff is what I want the oil to take out of the engine! Fresh oil, few heat cycles, and drop it. Second change...put a few dozen miles of driving on it(say, 2 round trips to town since that is 30 miles), drop it again, then just eyeball the dipstick while driving it on those short(relatively speaking) jaunts to town ironing out other minor issues inherent on bringing a 53 year old vehicle out of a 20 year slumber. Steering donut, evaluate the clutch, work on some wear in the column shifter, etc.

On that note, suggestions for a UOA lab that doesnt take three eons to run their tests? I'd like to know what my samples have in them BEFORE I'm ready to drop it again lolol
 
From what I've heard, it's wise to keep a spare onboard if you run with Pertronix.

There's always the points triggered HEI option, too, though I don't have any experience with that.
 
General motors made a decent high energy Ignition system that was contained in the distributor and it had the autotransformer in the cap, a solid state module in the distributor and metal with points that did not ever touch but conducted a magnetic field to triger the spark, and a Vacuum Advane. I owned a few of the eight cylinders of the seventies that had that system. I don't know what years gm made them for 6 cylinders, but it would be worth it to try to get one.

The weak part of those gm ignition systems was the thin wire of the timing pickup coil being flexed when the vacuum advance moved. They often broke around 70k miles. You have to pull the distributor to replace that coil. Sometimes the new metal with the points for magnetic timing were not made proper and resulted in too big of a gap and then the unit would not spark. Just transfer the new coil to the old metal coil housing and it would work every time.

If your going to install an old unit you mise-as-well put in a new pickup coil before installing it in the vehicle.
 
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