what oil, Pontiac 455 for best bearing protection

[ws6formula]

I have a 1978 Trans Am and I am looking for an oil brand and viscosity recommendation. Note, my Trans Am is not stock. I have added a stroker 455 crank to the original 400 and engine was completely rebuilt with Comp Cams hydraulic roller lifters (stock was hydraulic flat tappet lifters) - therefore, I don't think I need an oil with high Zinc/ZDDP. This is car's specifications: 1978 Trans Am, 400 Block / 455 stroker crank, forged rods and forged pistons, Ported cast iron cylinder heads, 9.3:1 compression, after market (Competition Cams) roller camshaft/roller hydraulic lifters, likely puts out around 450hp/500ft lbs torque...redlines around 5500rpm,main and rod bearing clearances are .002-.003, 3.42 rear axle, 4 speed Borg Warner Super T10 Manual Transmission. I have about $9,000 invested in the engine I will generally only drive the car on weekends and I will likely put only a few thousand miles on each year. Summer temps are around 80-85F. I will generally drive the car in nice (above 60 degree F weather), though will likely start/drive engine/car on cool fall nights and I will start/drive the card a few times during the winter when around 35-40F. I can change the oil frequently. I am not too concerned about the cost of the oil. Though, I like to get good value for money spent. I have read a little about oils like Amsoil, Royal Purple. These oils seem a bit pricey around $10/quart. I am not sure are they worth the higher cost. I am bit confused about using a syntethic oil. I use synthetic oil now exlusively in my newer cars. But, I have read that some have problems (perhaps seals/gaskets leaking a little when using synthetic oil in these older muscle car engines). I have read that synthetic blends may offer better start up protection without some of possible negative side effects (ie. possibly leaking seals/gaskets). I most concerned about protecting the engine from a spun bearing and avoiding problems with the thrust bearing. Given the above , can anyone recommend an oil brand and viscosity and perhaps say why you would recommend that oil ? Thanks

 

[spasm3]

I would really think about what thermostat you have in there ! if you are running a 180 i might go with a synthetic 30wt. If you are doing a 195 thermostat i'd run a 40w syn. Even with roller lifters what are the spring pressures on the cam? I'd base my zinc needs on the valve spring pressure. Modern gaskets should not be a problem for a syn, unless you got some new old stock.

 

[xxch4osxx]

Rotella T5 10w30 would be a great choice for your vehicle.

 

[Clevy]

A European spec 0w-40. Done.

 

[OVERKILL]

M1 0w-40 would be more than adequate for this application IMHO. Another option is M1 TDT 5w-40 if you want something a tad heavier. Seals and gaskets aren't an issue, particularly given that you've rebuilt it an these items are new. I've used both oils in a few built roller 302's, both my own and a buddy's and we've had great tear-down results with it.

 

[Red91]

QS Defy 10W-40 would be my vote.

 

[CarbonSteel]

Does have the rope seal on the rear main or a conversion to a modern seal? If a synthetic is desired, I would run Rotella T6 in 5W-40 which should provide ample protection.

 

[aquariuscsm]

I'd say a classic car formula 20W50.

 

[Bandito440]

There's a $5/gal rebate on gallons of Rotella T6 now, and they're $19.57 at Amazon and WM. A couple of $14.57 gallons of T6 will set you right.

 

[johnnydc]

You are going to get many suggestions. I myself am no expert. But My buddy runs Mobil 1 in his 1970 Chevelle I think 10w/30 or 10/40 can't remember. His engine is a very radical Chevy engine that puts out around 875hp at the crank. (Dino verified) He drag races every weekend and has not had problem 1 with motor. P.S. He has wasted a few trannys though... Basically you should be ok with otc name brand oils...........

 

[Clevy]

My uncle has a 1970 chevelle ls6 454. Very rare. 6 figures type rare. It's got 45000 miles iirc. He bought it new. Engine is still stock with original gaskets. He uses an hdeo in the 10w-30 flavour. No leaks yet and I think it's got a rope type gasket for the rear main seal. He has used a few flush type products to wash out the sludge that the oils of the 70s and 80s left inevitably. The car breaks the tires loose at will and was under rated from the factory. From what I've read the 70 chevelle was the only car to ever leave the general with more hp than the corvette.

 

[jk_636]

Royal Purple XPR is some good stuff that can take a real beating. It should offer more than enough protection for your motor. http://www.royalpurpleconsumer.com/products/xpr-racing-oil/ As for the weight, I would agree with those above. A good Xw40 would probably be your best bet.

 

[jdavis]

I'd go with an oil over 3.5 HTHS.

 

[clinebarger]

Originally Posted By: ws6formula

I most concerned about protecting the engine from a spun bearing and avoiding problems with the thrust bearing. Given the above , can anyone recommend an oil brand and viscosity and perhaps say why you would recommend that oil ? Thanks

The oil itself is not the reason Pontiac engine spin bearings, The large Main & Rod journal diameters is the main culprit. Your ahead of the game using a 3" 400 main bearing vs a 455 main size of 3.25". Does is still have the stock 2.25 rods? Or do you have 2.20" big block chevy rods? If your still running Pontiac rod journal diameter.....Stop spinning it over 5,000 RPM, 4,800 RPM would be an ideal redline. At 5,500 rpm....The journal to bearing speed is atrocious.

 

[Nickdfresh]

Just come over the border and get Mobil 1 High Mileage 10W-30 or 10W-40 and call it a day...

 

[ws6formula]

Thanks for all the replies and good information . Q: What are valve springs seat pressures ? A: I am using Comp Cams 995 valve springs. My roller cam has approx. .550" of lift on intake and exhaust. 115 lbs @ 1.700" installed height, 336 lbs @ 1.150 . Q: What thermostat ? A: Need to doublecheck, I thought it was a 160 degree (or 180 at most) . Q: What rear main seal ? A: I am using a newer style (called graphtite) rear main seal from Best Gasket, http://www.bestgasket.com/about_our_products.asp . Q: What con rods ? A: I am using aftermarket eagle rods, 6.8" in length, with 2.20" journal. The main journals are 3.00" . I am almost a bit scared to run a synthetic. But, it sounds like many successfully use and recommend synthetics in these type of engines.

 

[CarbonSteel]

Originally Posted By: ws6formula

Q: What rear main seal ? A: I am using a newer style (called graphtite) rear main seal from Best Gasket, http://www.bestgasket.com/about_our_products.asp

Ah, but still the "rope" style. I ran a 6.6L (400) and a 7.5L (455) in a 1980 T/A for a number of years and spent a substantial amount of money on both. I found that drilling the oil inlet holes in the main bearings to match the size of the main webbing hole saved the bearings from spinning. Most of the aftermarket oil pumps back in those days were high pressure as opposed to high volume and drilling the bearing holes increased the flow. I ran my 455 to 6500 with no issues, but I installed a MSD rev limiter to prevent anything above 6500. Nunzi Romano gave me tons of tips and tricks and supplied many of my go fast goodies (including a rubber rear main seal). Mine dyno'ed at over 500HP with nearly the same in torque. Pontiacs are like diesels in that they are low RPM with tons of torque. Best of luck with yours--it is good to still see the old Ponchos still on the road.

 

[ws6formula]

I know Pontiacs with larger journals (and cast rods?) could be a bit more prone to spinning bearings. I was hoping to get an oil (if possible) that could offer better protection against main and rod bearings spinning and protects my thrust bearing. I was thinking - get an oil that has a stronger oil film? or an oil film that resists breaking down better? or an oil where the oil film clings better to the bearings? Hopefully, this could help main/rod bearings from spinning and help protect the thrust bearing. If I could get an oil that offers this enhanced bearing protection, I would be more willing to sacrifice in other areas (ie. wear, clealiness, changing oil a bit more frequently, etc.). I may be totally off base here as I dont really understand this aspect of oil.

 

[CarbonSteel]

Originally Posted By: ws6formula

I know Pontiacs with larger journals (and cast rods?) could be a bit more prone to spinning bearings. I was hoping to get an oil (if possible) that could offer better protection against main and rod bearings spinning and protects my thrust bearing. I was thinking - get an oil that has a stronger oil film? or an oil film that resists breaking down better? or an oil where the oil film clings better to the bearings? Hopefully, this could help main/rod bearings from spinning and help protect the thrust bearing. If I could get an oil that offers this enhanced bearing protection, I would be more willing to sacrifice in other areas (ie. wear, clealiness, changing oil a bit more frequently, etc.). I may be totally off base here as I dont really understand this aspect of oil.

How many RPMs are you planning to run? If you are only driving it normally, this should not be an issue. HDEO oils would protect the bearings. I ran 10W-40 back in the day with an external oil cooler and had no problems.

 

[spasm3]

With an open seat pressure of 336 i might run a high zinc hdeo. With a temp of 160 a 30wt would do. Amsoil makes a HDD in 5w 30 thats a heavy duty diesel oil.