My 09 Tundra has 118,000 miles and I have been using Castrol Synthetic 5W20 for nearly the whole time since the truck was new. During normal driving the oil pressure gauge once warm stays just under the half way mark even when I come to a stop at a light after driving on the highway. The concern is that when I pull my 7200 lb trailer and get off of the highway and sit at a red light the pressure slowly drops to below the half, sometimes all the way to 1/4. No warning lights come on or anything and when the AC compressor kicks in and the engine revs a bit the pressure jumps again but then drops when idle comes down again. I know that the oil will be hotter towing than not but per the owners manual 5W20 or even 0W20 is good in these trucks for towing as well. Also never did this before when newer or at least I never noticed when the truck was newer.
Does anyone else's Tundra do this or am I starting to see a problem? Truck doesn't use any oil between changes and always change at 5000 miles.
If I take it to the dealer I am concerned that they can't repeat it as they will not be towing.
Is this a problem with mileage getting higher or am I just noticing a perfectly normal thing on the truck due to higher towing temperatures on the oil?
Thanks for any insight,
Since the oil pressure returns to just below half gauge at idle when not towing, and no warning ever comes on, I wouldn't worry about it.
It's true that at 118K miles, your truck isn't new anymore, but oil pressure just below half gauge at idle is excellent in my opinion. I haven't been able to determine the actual range of the oil pressure gauges so far, but I suspect half gauge is about 20 psi. Typical engine oil pressures on older vehicles may
be as low as 5-7 psi, and that's adequate for the no-load condition...yours is clearly higher than that if I'm right about 20 psi at half gauge.
As to what's causing the oil pressure to be lower when you tow, I haven't any idea. I doubt it's because of higher oil temperatures, bwdik. It seems to me 0W20 means it's 20 weight oil at normal operating temps, and towing is a normal
What's your coolant temperature doing when you tow? I would suspect increased pressure drop somewhere in the oil system; e.g., is there an engine oil cooler that may only come into play when you're towing?