I have a 1999 Durango 5.2lt. 4x4. With 110K on it. Got the truck with 78K on it. About a year ago I noticed the oil pressure guage would change readings just going down highway at a steady speed. Then return to normal. I changed the sender as a quick try but to no change. I did an early oil change next and it was OK for about 500 mile then acted up again but also during city driving, after about 20 minutes of driving. Next I pulled the pan and changed the pump and screen. I was actually amazed how clean it was inside. There was no sign of any metallic partical or slug at all in the bottom end. I have always changed the oil about 3500 to 4000 miles. I just did another oil service to it two weeks ago and within 300 miles the problem has reaccured. There has been just over 7000 put on it since the last fix. I have alway used Penns high mileage 10w40 in it with NAPA Gold filter. Any ideas other then pull and go through motor would be great. Jim

 

Switch back to OEM recomended 10w30 and check out your oil pressure sensor. You can also try plumbing in a separate gauge to see if it is giving you an accurate reading as well.

 

Do you live in a cold area? I usually do 10-30 in Summer and 0/5-30 in Winter.



If you're really worried, I would just quickly hook up a mechanical gauge to get an accurate reading for it.

 

OEM recommends 0 F - 110 F is SAE 10W-30 (Prefered) or for winter use and abundent temp lower than and average of 32 F to use SAE 5W-30.

The fact of the matter is this; If you use Fully Synthetic Oil then it is shown to flow like water to -58 F and therefore is 10 times better than regular lubricant (oil). In this case then you should run the 10w-30 all the time.

Now here is your problem that you might have created. Going into the basis of the 5.2L and the 5.9L block that has been used since about 1962 10W-40 was the standered lubricant and is the only one that has the proper additives in it other than 10W-30 to make it VERY close.

Now oil 101: Oil is made out of oil base. Other words all regular gear lube like 80-90W and 0W-20 uses the same oil base, it has different additives blended into it for the different applications therefore creating different lubes and different weights. I do not like the 5W-30 application because I can't see that they incoporate the same additives even tho the OEM says it is ok. (my opinion)

Now you used a heavyer lubricant for 30k miles (NOTE: that does have the additives) but the problem with 10W-40 it is heavy and the additives break down fast and this concludes why it is slowly being discontinued and vehicals are no longer requiring it.

Now if one uses it long enough premature ware can occur. I think the problem is that the main bearings are starting to show more ware hintz the eqilization of pressure. Now as a motor increases in RPM there will have a upped pressure up to about 10 psi and can fuxuate somewhat. Also I have noticed that the NAPA Gold Filters run higher psi than OEM (which is a good one).

I would recommend returning to a 10W-30 Fully Synthetic Oil and a good filter like OEM.