s_dime_man Posted March 21, 2008 Report Share Posted March 21, 2008 just swapped engines in a quest.. changed oil and with in 800 miles my oil is very black. why? and i have went through 2 used slave cyl. for clutch these commonly go out?? Link to comment Share on other sites More sharing options...
Fanta Posted March 21, 2008 Report Share Posted March 21, 2008 do a compression test - does the oil smell anything like gas? Link to comment Share on other sites More sharing options...
Hoosierquest Posted March 21, 2008 Report Share Posted March 21, 2008 I have noticed oil in a turbo car blackens before an NA. With the slave cyl dont get a used one you are wasting your time. just go to your parts store and pick up a rebuild kit. They are like $7.00 and only take minutes to complete. Link to comment Share on other sites More sharing options...
Whiplash Posted March 21, 2008 Report Share Posted March 21, 2008 Studies have shown that black oil doesn'y mean that it's old and burnt. Was the swap a new rebuild or used? Link to comment Share on other sites More sharing options...
Wolf87Conquest Posted March 22, 2008 Report Share Posted March 22, 2008 Oil in a turbo car will blacken quickly. The high heat in the turbo, oil circulated to the turbo for lubrication and cooling have this effect. Todays oils have a good bit of detergents in them, again, will darken the oil. If the engine is a fresh rebuild, blow by gases around the rings until they seat will cause oil to blacken even quicker. If the oil comes out kinda like water with little viscosity left, it's been kept at to high a temp and it's broken it down. Your oil cooler may not be functioning properly. Clogged or the thermostat on cooler is stuck closed. Link to comment Share on other sites More sharing options...
s_dime_man Posted March 22, 2008 Author Report Share Posted March 22, 2008 ok so what should my compression test psi be? gimme new motor and 150,000 mile motor numbers i will do the test in the morning.... thanks guys Link to comment Share on other sites More sharing options...
Caliber308 Posted March 22, 2008 Report Share Posted March 22, 2008 Dont forget that the oil filter holds 1/2 quart, and the oil cooler holds 1/2 quart. So if you changed the oil without changing the filter and draining the oil cooler. You have 4 quarts of new oil mixed with one quart of old oil. CALIBER 308 Link to comment Share on other sites More sharing options...
Fanta Posted March 22, 2008 Report Share Posted March 22, 2008 ok so what should my compression test psi be? gimme new motor and 150,000 mile motor numbers i will do the test in the morning.... thanks guys Being that it is stock, I believe 115psi with a 5% margin of error ( meaning your compression can be higher or lower than that within 5% and its okay ) Others have brought up good points as well - there are a few factors that play in to it all. You may just be freaking out for no reason like I have on occasion Link to comment Share on other sites More sharing options...
Indiana Posted March 22, 2008 Report Share Posted March 22, 2008 no one brought up ventilated versus closed crankcase with synthetic versus non-synthetic oil and how often you should change it synthetic oil is better for turbo cartridge heat but it has less detergents for reduced foaming the detergent is what suspends the crap and causes the oil to get darker and darker and darker if the crap isn't suspended in the oil where do you suppose its goes? if you use check valves your crankcase is NOT ventilated Link to comment Share on other sites More sharing options...
Dad Posted March 22, 2008 Report Share Posted March 22, 2008 no one brought up ventilated versus closed crankcase with synthetic versus non-synthetic oil and how often you should change it synthetic oil is better for turbo cartridge heat but it has less detergents for reduced foaming the detergent is what suspends the crap and causes the oil to get darker and darker and darker if the crap isn't suspended in the oil where do you suppose its goes? if you use check valves your crankcase is NOT ventilated Mine turned black pretty quick, but i blame the Machine shop for not doing a good job. I just plan on changing it every 2k miles, maybe every 1500 if i run it hard, Oil and filters are cheap Dad Link to comment Share on other sites More sharing options...
Caliber308 Posted March 23, 2008 Report Share Posted March 23, 2008 (edited) Mine turned black pretty quick, but i blame the Machine shop for not doing a good job. I just plan on changing it every 2k miles, maybe every 1500 if i run it hard, Oil and filters are cheap Dad I change mine every 1500 miles. Im using Castrol GTX 20/50wt. And yes, I do change the oil filter every time. When I did a high performance rebuild on a 1973 Harley engine, I used Kendall super 70 racing oil 50 wt. You should see that crap come out of the can. It looks almost black, but has a greenish tint to it. Ran Aviation fuel in it (130 octane) at a 50/50 mix with 90. It was a kick in the a--. CALIBER 308 Edited March 23, 2008 by Caliber308 Link to comment Share on other sites More sharing options...
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