1985 suburban mark iv 454 build. What oil do you guys like?

Txaggie76 said:
Thanks! Since we built it for towing, the cam’s power band is 1200-5000 rpm.
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I supplied Howard’s in Oshkosh, WI about 300 of their lobes 20 years ago. None of them had odd numbers @.050”.
213/221 in at 108 Int -2/35 Exh 47/-6 if I still remember how to do the math.

Just in case you’re one of those guys who blocks off the stock oil filter by-pass, use a #9100 filter from a Duramax.
 
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Txaggie76 said:
What are y’all’s thoughts on still using gp1 but changing to 20w50?
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What are your rod and main bearing clearances? If less than .003” xW40 will do ya. Did you install a high volume pump with the high pressure spring and pinned pump drive?
The issue I have with 20w50 is the time it takes to reach the rockers then run down onto the camshaft.
A scene often witnessed on the beach are big blocks sending their crankshafts to the bottom of the lake because the owners started the engines and went to full throttle 30 seconds later to show off to the girls.
The cautionary tale is give your BBC some warm up time at moderate load to warm up the oil.
For continuous operation above 3,500 rpm, get rid of the stock harmonic balancer.
A stock 20 year old one won’t work properly and is a cause of cranks breaking right behind number two rod journal.

Nowadays, I wouldn’t be adverse to using 5w50 Dexos R or one with an A3/B4 approval. Their HTHS is high enough for your bearing clearances and the VIIs will keep the oil pressure high when it gets hot.

Another engine oil proven over time is good old $4 Delo 400 SAE 40 as long as start up temperatures are above 40F.
 
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userfriendly said:
What are your rod and main bearing clearances? If less than .003” xW40 will do ya. Did you install a high volume pump with the high pressure spring and pinned pump drive?
The issue I have with 20w50 is the time it takes to reach the rockers then run down onto the camshaft.
A scene often witnessed on the beach are big blocks sending their crankshafts to the bottom of the lake because the owners started the engines and went to full throttle 30 seconds later to show off to the girls.
The cautionary tale is give your BBC some warm up time at moderate load to warm up the oil.
For continuous operation above 3,500 rpm, get rid of the stock harmonic balancer.
A stock 20 year old one won’t work properly and is a cause of cranks breaking right behind number two rod journal.

Nowadays, I wouldn’t be adverse to using 5w50 Dexos R or one with an A3/B4 approval. Their HTHS is high enough for your bearing clearances and the VIIs will keep the oil pressure high when it gets hot.

Another engine oil proven over time is good old $4 Delo 400 SAE 40 as long as start up temperatures are above 40F.
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Maybe Mobil 1 15w50 would be good then?
 
Txaggie76 said:
Maybe Mobil 1 15w50 would be good then?
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Back in the day we could get Delvac 15W50 with high saps. I used it in my son’s 350 sbc on propane changing it every 40 thousand miles or so, more for a filter change when the oil was down a quart anyway.
After 10 years the half ton van fell apart around a good running engine.
Once again, if your oil filter bypass is plugged, use an oil filter with a bypass like the 9100s from a Duramax.
 
Sweet Suburban! Love the look and the wheels!

My 454 was thirsty too, but she was worn out from towing prior to me getting it and installing in my truck. I fed it a diet of cheap diesel 15w-40 and never had an issue. But again, mine was worn out.
 
Cujet said:
The 15W-50 is on the low end of the viscosity scale. Including during typical cold starts in reasonable climates. Even so, a post above mentioned that it is a good idea to warm up properly before making the engine work hard.
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Thanks!

I contacted driven and they recommended I go with their 20w50. My bearings are standard size in the rebuild.
 
Cujet said:
The 15W-50 is on the low end of the viscosity scale. Including during typical cold starts in reasonable climates. Even so, a post above mentioned that it is a good idea to warm up properly before making the engine work hard.
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I’m in central Texas so definitely a warmer climate 90 percent of the time.
 
Good choice to go with a mild aftermarket roller cam, 80s big blocks fall off around 3000-3500 with the stock hydraulic flat tappet cams. I worked on many gutless lifted C20s back in the day. You'll never need to worry about zinc with the roller either, so that's a win. Howards is underrated, had good luck with them in the past.

As for the oil burning, what did you set the ring end gap to? Hopefully you checked it?
 
With those cam specs engine vacuum is probably 20 21 inches at idle so a longer break in isn't surprising. Agree with thicker lube in hot ambient. Experience here with 6 BB rebuilds over 30 years has shown up to 10,000 miles for break in.
 
Dinoburner said:
With those cam specs engine vacuum is probably 20 21 inches at idle so a longer break in isn't surprising. Agree with thicker lube in hot ambient. Experience here with 6 BB rebuilds over 30 years has shown up to 10,000 miles for break in.
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Thanks! What are your thoughts on me going Mobil 1 15w50 full syn?
 
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