Oil Viscosity Question?

My truck calls for 10W-30 and in Florida I don't need to worry about operation below freezing hardly at all. I have been running 20W-50 in most of my trucks because it often sees operation in temperatures above 90
degrees and above 100 in the summer. I know that on startu-up 10W-30 reaches the bearings quicker, but wouldn't 20W-50 give it more protection in high heat conditions? Also, I noticed the new 5W-30 oils out there. All Data has the 5W-30 listed as an option in my truck. Is there any advantage to 5W-30 over the others? I would think the thinner oil wouldn't protect as well under harsh conditions like 4 wheeling or towing a trailer. I would appreciate you comments. I currently run Castrol 20W-50. I would never use Quaker State after rebuilding my fair share of Quaker State engines with an inch or two of sludge build up from the parafins in QS.
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similar conditions. I've also had several go well past the 200k mark on 10w30. if you look in your owners manual there is a chart that shows what oil viscosity for what temp range. the 10w30 should cover your area fine. your summer time temps would be in the upper half of the 5w30 range. IRRC
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My last truck was a Chevy, but Castrol 20 W 50 was the only thing that quieted the rod knock more than two days after an oil change.
Hadn't heard that about Quaker Sludge oil.
I'd stay with the Castrol 20 W 50 if it were my vehicle. Why do you bother to ask? I someone trying to get you to use something less effective?
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Use 10w30. Pressure means nothing, flow means everything. Your engine use very small clearances, hence the lower viscosity oil. Do not use 20-50, inadequate flow will be the result at the front of the engine. Your sludge story is a wives tail. Sludge is common when inadequate warming of the oil occurs. It is created because condensated water combines with the residual sulfer in the oil. This creates sulfuric acid which corrodes the oil and turns the oil to sludge. This process can occur with any brand oil that contains sulfur. This condition is normally caused by people who remove the thermostat. Did you do that? Steve

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No, I didn't remove the thermostat. I was talking about motors that I rebuilt back in the 80's and the ones that had Quaker Stae had sludge extremely thick in the valve train. I thought it was the type of oil with parafin wax in it. I guess it was just a coincidence that the QS motors had the worst build up. Unless they have more sulfur in their oil.

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Oil is designed to separate metal. Like piston rod and crankshaft.
An oil which holds the two apart is also like to read as pressure. If you put in a no viscosity oil, you can have a lot of fluid flowing. But not much lubricating. And not much pressure. So, you would have great flow, but wear out the engine.
I think oil pressure isn't a guarantee of protection. But a non-protecting oil is likely to read low or no pressure.
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DJ wrote:

and no more. Extra thick oil does not provide extra protection, it takes more energy to move it around, and puts excess strain on the pump and pump drive mechanisms. I run 5W-30 in my truck year round. In the summer I often tow a trailer in temps to the high 90's. In the winter it only gets down to about 0*. Oil pressure is always right where it should be. Still running great after 82K miles.
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Remember also that the worst wear occurs on cold startup. 5W30 would be best for an engine in good condition since it would minimize startup wear and still increase its viscosity to the higher number as engine temperature builds. 20W50 would result in poor flow on startup, with increased wear as a result.
As the miles on the engine climb higher and clearances increase, 10W30 might be a good step since it's a smaller range of viscosity and therefore should have less additives which contribute to deposits. What do you think?

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Yea, that sounds like the consensus. I also read about the different oil filters and they listed the Fram filters as one of the worst. I replaced it with a Mobil1 filter (Made by Champion) and the oil pressure increased by 25psi. Now it rides at 3000rps at 45psi after reaching normal operating temperature where it was riding at 20psi. It would start cold and run right at 40psi and now when the engine is first started cold it runs 60-65psi. The filter made that much difference. I got the Mobil1 because I couldn't get a WIX at the local parts store. I found out the NAPA Gold filters are actually WIX filters with the NAPA Gold branding. The whole oil pressure problem started after an oil change at Texaco Quicl Lube. It would sit on 0 psi at idle. I swaped it out for the Fram Extra Guard and then had the oil pressure riding at the low end of the scale. I have never had a problem with the oil pressure in my other trucks (not a Dodge) running Fram filters, so I didn't know about the huge difference a filter can make.

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Wow, 0 at idle?! Fram or not, that sounds like a defective oil filter. That's great that you caught it!
I think I recall that Fram uses too much flimsy cardboard and plastic where Wix and others use better materials.
You can also get an oil pressure and volume boost by running the larger oil filter rather than the current "shorty" type Chrysler switched to back in the 80's. Forgive the Fram part numbers -- but I think the shorty is PH16 and the larger one is PH8.

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Marcus wrote:

Dodge and Ford have the mounting boss for their small block V8's. Anything that fits a SBF, will fit 5.2/5.9. I generally use Purolater Pro-1, their premium blue filter. Rate among the top 2-3, and easy to find. They often go on sale at Pep Boys.
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Marcus wrote:

temperature range in your area and a good filter. My guess would be 10w-30 down south. I also suggest that you go with a good synthetic oil as well. A good synthetic oil and filter will provide better lubrication and last longer than regular motor oils. As a side benefit, the base stock for most synthetics doesn't come from the oil field.
Amsoil's website has a lot of good information. Their website is www.amsoil.com.
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