What Oil for a 6.6L 78 Transam

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Hi all, Just wondering what is the best weight and tpe of oil to use in a 1978 or there abouts V8 6.6L Pontiac Trans am. Driven in Australia, Queensland, rough temps in F would be 114 summer and 23 Winter.
 
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hey, i owned a 76 t/a w/pontiac 455 4bbl and a 78 t/a w/pontiac 400 4bbl [6.6l] i used 10w/40 dino in both.is yours the pontiac 400 or olds 403? ... [ February 22, 2004, 08:05 AM: Message edited by: moontan ]
 
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[Cool] Wow, that's hot! I'd say use 10w-30 in winter and 15w-40 or 50 in summer. Maybe run some Auto-RX through it to condition the seals and then use Mobil 1.
 
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quote:
Originally posted by Francis: Hi all, Just wondering what is the best weight and tpe of oil to use in a 1978 or there abouts V8 6.6L Pontiac Trans am. Driven in Australia, Queensland, rough temps in F would be 114 summer and 23 Winter.
Do you want to run synthetic or mineral/conventional oil? What oil are you running now? How is consumption with this oil? Where are our Australia boys at? I don't know quite all what's available to you down there, but if this was my ride. Conventional - HDEO 15w-40, period! Synthetic - 5w-40 HDEO, or 15w-50 and 20w-50 PCEO's.
 
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as i mentioned about the t/a's i owned [ in the early 80's, in maryland] i used 10w/40 pennzoil or castrol. but i have to agree w/ jelly. synthetic if your seals & gaskets are up to par.. [ February 23, 2004, 02:14 AM: Message edited by: moontan ]
 

Francis

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Hi, thanks all for the replies. It's for a mate that asked me so I asked you's. Those Temps are a High of summer and the Low of Winter so it's not always that hot or cold here. Um, I'm not sure if it's the Pontiac or Olds engine. 1: Mineral first choice, I know you guy's all hate them, but all the High Performance part manufactures, speed shops and engine builders, and even a lot of oil companies tend to say that in those American 60’s 70 style, large clearance, old push rod V8, high lift engines, you get better protection out of regularly changing a Mineral oil often than a full Syn. still say to use them. Even Crower Cams and Cranks have a bit on there site saying use a quality Mineral oil, as the effect on ware with syn for out way the HP gains. Plus and we have a huge range of performance based minerals here, so I don’t know, but heaps of people use them and have for years, plus I also prefer to change my oil more often and have a clean engine with clean oil than a long drain interval one.. I think he is using Penrite HPR 30 that’s a 20w 60, very widely used, and Penrite is a company that goes out of it's way to prove you don’t need to run Syn's to have a top rate performance oil. Check them out at www.penrtie.com.au, go to the HPR range and have a look. I don’t think it's using much oil at this stage. Thanks for all your help everyone. Those Trans-am’s are such a tuff looking car! I would love to own one, but in Australia they pull big money. I'd love an 84 Trans-am but they also are still so expensive.
 
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I'm runnin a 74 Pontiac Grand Am (400, 4B Quadrajet), with some 10w-40 mobil (dino). Well pretty much for the last 100,000 miles. I think the car's going on 300k now? I dont't even remember anymore, the damn odometer's rolled over more then once [Smile] . One thing you might want to watch out for with syn's in the old pontiac engines...they've got that damn neoprene rope thing as the rear main seal.. http://www.chevytrucks.org/tech/bobadler-1.htm These tend to start leaking as early as 20k after an engine rebuild (if the engine was rebuilt before the nice seals came out)...and with synthetic, the oil will leak MUCH faster. Damn well flowing synthetic!!!!!
 
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