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the best oil for turbo

3262 Views 12 Replies 9 Participants Last post by  dogstar
what would be the best oil to use on the 7mgte motor? synthetic or non-synthetic and why?

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depends if its a fresh rebuild or a high mileage motor. if its a fresh rebuild and money is no object, amsoil synthetic 10w-40. if its a higher mileage motor, prolly castrol gtx 20w50.
why wouldnt synthetic be good for the high mileage engine?

Syn doesnt cause oil leaks but when used in an engine that has questionable seals ie cam seals, crank seals, cam tower, etc. will tend to leak more than dino oil. This is due to syn having a lower coefficient of friction compared to the same wieght of dino oil, its just more slippery!!
with a turbo application i have always stuck w/ regular 20/50w oil and change it every 1500-2000 miles and swaping out the filter every other time. i've never liked the synthetic oils, i have seen them cause residue build up unlike the 20/50w. i stay w/ good dependable oil school oil for an old scholl car.
"slide your ride"
well, i got the motor in my first 85 rebuilt when i was in hs after it started knocking. i used castrol syntec 5w50 and changed it ~every 1kmiles just because of how i drive my cars and always changed the filter at the same time. never had 1 problem. and ask anyone that knows me, i drive my cars like im trying to blow them up(actually succeeded once, but due to an existing engine problem i was unaware of). as for a higher milage motor, dont use syntetic as its likely to develop leaks as mentioned earlier.
The heat that oil sees going through the turbo bearings will break down "dino" oil faster than synthetic. If you use "dino" oil on a turbocharged engine make sure to check it often and change it as soon as is gets dark.

I like typing "dino".

The only reason that Synthetic causes oil leaks is because the seals in an engine become "conditioned" by the "dino" oil and swell for a tight seal. After am umpteen thousand miles of driving the swelled seals wear a bit. Most synthetic oils do not cause the seals to swell as much as "dead dinosaure" so over a short amount of time the seals shrink and ... leaks start.

Most of the "high milage" sythetic oils have aditives to swell seals to prevent new leaks from forming. Using regular oil and changing more frequently will work ... but it's still not synthetic. The two major enemas (enemeys) for oil are heat and high shear rate. In a turbo, the [email protected]*&ing things glow red hot, and spin at 60,000RPM. The shear rate alone will destroy the protecting properties of regular oil never mind adding heat. Personally, I would be worried about sludge from broken down dinosaure instead of the other way around.

The topic of oil has been discussed before on the forumn and always has a number of different opinions. Do your homework ... and decide for yourself. :wink:

Your right! typing dino IS FUN!
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actually, the ct26 spins up to 120krpm's.
I've read everything from 40,000 RPM to 250,000 RPM. I thought I would be conservative because I hate it when people exaggerate numbers to scare people into believing them. Still it's good to know I went WAY to conservative.

Has any body had a problem with oil starvation to the cams of 5M-GE engines using 20W50??? I’ve used that weight in my motorcycles ‘cause they ran hot as hell, but I’m in a chili area of Canada and am afraid to use it. I’m using 10W30 for winter and am thinking about running 20W50 in the summer. Any thoughts???

i always use valvoline 20w-50 regardless of weather. but then again i live in Georgia.
morganism... ive been using 5w30 for this first winter here, and im finding it stops the valve clatter sooner than 10w30, even when doing the double start trick.

now, for me, valve clatter = not enough oil up there, so i figure the less noise, the better.

also, IIRC the manual recommends 5w30 for winter in cold climates, but i might be wrong, its been a while.
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