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I live in high desert in So. California and the weather temperature usually go 90's to 100's during the summer. I need to know which one would be the best for my '71 with 429 rebuilt engine (about 600 miles). I just changed the oil with 5W-30 about 100 miles ago. Should I change the oil again for more weight? Which one is suitable for my car? Thanks.
 

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Given the temps, I'd run 20-50. I run Valvoline 20-50 synthetic blend in my 302 year round.
 
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5w30 if you plan on moving to the Dakotas. With temps in the 90's I would go the 20w50 route
 

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We have a house in Rosamond and live in Santa Monica. If your engine is broken in I would use a synthetic exclusively! My favorite is Mobil One or Castrol Syntec. Used to say to change oil once a year or 24,000 miles. I change once a year and filter every 3,000. Been using them since they came out in the 70's in off road VW race cars. The stories I could tell about how they saved several engines including my current Mustang daily driver. 20W-50.
 
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Yeah, I live in Rosamond and I guess you know what it's like.

You guys got me. I'll go with 20W-50. What was I thinking? South Dakota? Yeah, right.
 

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Mobil 1 has a nice 15-50 blend . I run that in my Katana 1100.
 

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20W-50. You may consider running AMSOIL versus Mobil 1. It does cost more, but it also holds up better.

I am presently running Castrol 20W-50 in my Mustang. I change the oil and filter every 2000 miles. I would switch to synthetic, but the motor presently has 115k on a rebuild and it uses a quart about every 500 miles...(probably baked valve guide seals and I have been too lazy to replace them - again)

Actually, you would need to run 20W-50 in South Dakota from June - October/forums/images/icons/smile.gif. Then you would have to switch to 0W-30.../forums/images/icons/wink.gif...
 

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'68 owner's manual says to use 10W-30 for -10 deg F to +90 F and to use 20W-40 for above 32 F. also says for siingle viscosity oil to use 40 above 90 degrees.
 

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Since you have rebuilt engine I wouldn't run too thick. Doesn't flow and build up pressure from start as fast as lighter. Robs hp too. HIgh desert, do you have cold mornings every now and then?? If so definitely use multigrade. 10W40 fully synthetic should be enough unless you do road racing or drive hard on twisty roads with high rpm. If in doubt, install mechanical oil pressure gauge, if you get 50psi at 5000rpm you're ok.
 

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Wow.....changes oil once a year and new oil filter every 3000 miles?? hmmmm talk about cost control!!!!!

I am running normal castrol 10-40 until the 342 stroker breaks in.......then I will switch over to redline synthetic. (multiweight)

keep your oil clean and check it often!!!!

regards
 
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