What would be considered safe max spread...
Logistics Pro
Joined: Jan 2010
Posts: 4,100
Likes: 1,635
This is correct, 20° is the max acceptable number. It may not cause any damage, but at a 20° difference it can be assumed that the oil cooler is plugged.
If your picture is of your temp spread at operating temps and doesn't go up much when at WOT or while loaded, then I'd say you're fine.
If you DO get a plugged oil cooler, I suggest biting the bullet and getting an oil cooler relocation kit. It gets the oil cooler out of the engine valley, which gets it away from the heat and helps prolong the life, as well as making it easier to replace if it ever clogs again.
If your picture is of your temp spread at operating temps and doesn't go up much when at WOT or while loaded, then I'd say you're fine.
If you DO get a plugged oil cooler, I suggest biting the bullet and getting an oil cooler relocation kit. It gets the oil cooler out of the engine valley, which gets it away from the heat and helps prolong the life, as well as making it easier to replace if it ever clogs again.
Fleet Mechanic
Joined: Sep 2006
Posts: 1,491
Likes: 295
From: Fresno, CA
The general rule of thumb that's been accepted over the years is 20+ minutes running 65mph on flat ground your delta shouldn't be higher than 12F. Running higher or lower speeds can increase/decrease the spread. Higher ambient temps can push the EOT a little higher as well. I usually run 9-10 during the summer and 7-8 during the winter with a consistent 192ECT.
Also assumes your thermostat is functioning correctly running an ECT around 190-192. When I purchased my truck the thermostat was running around 175F with a 190F EOT. I assumed the oil cooler was shot and purchased accordingly. Replaced the thermostat first and voila I'm running 192ECT and 200EOT.
OP your thermostat needs to be replaced. Needs to be above 190F running down the road. I believe the PCM adds fuel at anything below 186. Unfortunately even the motorcraft ones are known for lasting more than a few years.
Also assumes your thermostat is functioning correctly running an ECT around 190-192. When I purchased my truck the thermostat was running around 175F with a 190F EOT. I assumed the oil cooler was shot and purchased accordingly. Replaced the thermostat first and voila I'm running 192ECT and 200EOT.
OP your thermostat needs to be replaced. Needs to be above 190F running down the road. I believe the PCM adds fuel at anything below 186. Unfortunately even the motorcraft ones are known for lasting more than a few years.
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TBird Larry
1957 - 1960 F100 & Larger F-Series Trucks
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Aug 15, 2014 12:43 PM
