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02-20-2015, 05:59 PM
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#1 |
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Registered User
Join Date: Jan 2015
Location: abbotsford
Posts: 39
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oil issues need help
I have an issue and I think it was my fault. I recently bought a 69 c10 with a higher mileage 350 in it. after getting it I changed the oil to 5w-30 synthetic. Shortly after I got a rear main seal leak. I had just replaced the rear main seal. And the oil has again found its way out. It only starts leaking once engine is all warmed up. So my question would be. should I have a thicker oil? if so what should I go with and should I go back to conventional oil as well?
Thanks. Kyle |
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02-20-2015, 08:24 PM
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#2 |
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Registered User
Join Date: Nov 2014
Location: Dickinson, ND
Posts: 197
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Re: oil issues need help
A vehicle of that vintage, and particularly one with high mileage should not have 5W oil in it. The synthetic is neither here nor there. I would switch over to Catrol GTX "high mileage" 10W 30 motor oil. The older motors were designed around 10W 30.
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02-20-2015, 08:25 PM
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#3 |
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Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: oil issues need help
My suggestion would be to check the PCV system out before changing the oil.
If the PCV is not working properly, pressure will build up in the crankcase causing oil leaks to occur. Jim
__________________
1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC |
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02-20-2015, 08:34 PM
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#4 |
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Registered User
Join Date: Jan 2009
Location: Calgary, AB
Posts: 1,181
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Re: oil issues need help
Synthetic oil shouldn't be used on high mileage motors. You've found 1 good reason why.
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02-20-2015, 09:13 PM
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#5 |
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Registered User
Join Date: Jun 2011
Location: Spokane, WA
Posts: 2,372
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Re: oil issues need help
It's not leaking because of the kind of oil you have. How did you lay that new seal in there? I suppose it could be crank case pressure but unless you've got it all blocked off I doubt it.
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'77 K30 3+3 - "The Crummy" http://67-72chevytrucks.com/vboard/s...d.php?t=640134 '67 C10 L/SWB - Soon to be daily driver! http://67-72chevytrucks.com/vboard/s...d.php?t=471776 
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02-20-2015, 09:33 PM
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#6 |
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Registered User
Join Date: Jun 2010
Location: Upland Ca
Posts: 4,147
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Re: oil issues need help
One bottle of Lucas or Hyperlube and straight 30W.
__________________
1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
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02-20-2015, 10:14 PM
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#7 |
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Registered User
Join Date: May 2013
Location: Post Falls, ID
Posts: 898
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Re: oil issues need help
Eric "The Car Guy" explains, in lamen's terms:
http://youtu.be/3zEBI1QndPo Last edited by Greasey Harley; 02-20-2015 at 10:26 PM. |
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