Had the dreaded lower intake manifold failure so I wound up with coolant in the oil. I did the R/R with the FelPro gasket set along with 3 oil changes and the repair is doing well. The only thing that I see as a consequence of this is a lower oil pressure at hot idle. New 5W30 Penzoil dino yellow bottle with K&N filter. 40psi hot 2,000 rpm/20psi hot idle.

Whats the theories here on thicker oil, additives, new pump, drop/clean pan and screen, etc - or do nothing and stick with 10 psi/1,000 rpm? Just changed the sending unit cuz the original started leaking oil. Same readings.

Thanks,

George
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During hot months, I routinely go with thicker oil. I use 10W30 in vehicles that spec 5W30 as the preferred oil and can "tolerate" 10W30.

In older vehicles that normally get 10W30 I go to 15W40 or even 20W50.

Also, unless I'm making the change before 75,000 total miles, I don't switch to synthetic or "high mileage" semi-synthetic blends. Those high mileage blends are great oils, and if you switch between 60K and 75K, the are great. If you have 200K on the clock, you probably have cracks in the seals that are filled with conventional oil gunk and that's all that keeps them from leaking. Switching to "High mileage" or full synthetic oil at that point unmasks all the damage that has already occured, and results in leaks everywhere.

 

I have one more oil change this week for the water removal portion of this adventure so I will try 10W30 and see what happens. I will stick with PYB as it got me to 200,000 with good compression and until the lower intake manifold problem, good oil pressure.

Thanks,

George

 

I am going to have to completely disagree with you on this.

high mileage oil is a waste of money, first off.

And you can switch to full synthetic at any point in your vehicles life span. It will NOT cause leaks, this myth has been debunked by many people, many times.

My 94 blazer had 180,000 miles on the clock and I switched it over to synthetic with no issue at all, my 93 GMC jimmy had 164,000 miles on it when I switch it over to full synthetic without an issue as well. Both of them made it over 210,000 miles before we got rid of them, and they were still running strong when we did get rid of them.

 

Did you see any benefits in changing to synthetic oil in your high mileage vehicles?

 

The benefits of full synthetic oils are well documented.

• Better flow characteristics when cold
• Better lubricity (slipperiness) when extremely hot
• Lower friction overall, resulting in increased engine efficiency, possibly slightly better fuel economy, and lower operating temperatures in extreme use such as towing a heavy trailer.
• Much longer service life. Even in "severe" driving, you can run most full synthetics at least 7,500 miles, and some will run 10,000 or even 15,000 miles without loss of performance. They also last longer in parked/sitting vehicles, at least 12 months between changes is possible with full synthetics.

To take full advantage of the extended service life of full synthetic oils, you need to use a filter designed for extended service intervals like the Wix XP filters or Mobil 1 filters or Bosch "Distance Plus" filters. Alternatively, with standard filters you can change out the filter only at the "normal" change interval and run the synthetic oil for 2 or 3 filter changes. If you do that, obviously, you top up with fresh oil to replace what is lost with a filter change.

I insist on full synthetic oil for any motor homes that are brought to me, or any "trailer haulers." I won't put conventional oil in those vehicles. If you want cheap, take them to someone else.

"High Mileage" oils have more detergents, and some additional "seal conditioning" additives. They aren't a "waste of money" in my opinion. For "Grocery getters" and "Moms' Taxis," they are a good choice to extend the problem-free life of the engine. They aren't for extended use, and they aren't for high stress, severe use. With "high mileage" oils you still need to stick with the 3000 mile oil changes, and they don't offer the advantages of full synthetics I outlined above.

richphotos, I never said that synthetic oils (or "high mileage" oils) cause leaks. I said that if your seals and gaskets are old, hard, and might already have cracks, synthetic oils will stop masking the cracks and leaks you already have, and clean out the varnish and "sludge" that is plugging the leaks. It sounds like you've been lucky, or you've had vehicles that were well maintained prior to your switchover to synthetics.

I'll also say that I have successfully switched over high mileage engines (as high as 300K miles) to full synthetic oils. Before I even thought of putting the full synthetic in, I pulled a valve cover and inspected the gasket. If the gasket was a rubber gasket, and it was soft and pliable, but not swollen and spongy, then it's very likely the seals and other gaskets are still in good shape, and you won't have leakage issues with full synthetic. If the valve cover gasket is in good shape, I visually inspect the front crankshaft seal, and again if it's in good shape, not hardened and cracked, I'll switch to full synthetic. I've had a couple of those develop leakage after the switch, but that's pretty rare.

If the valve cover gasket is rubber, or more accurately, "was once made of rubber," but is already brittle and cracking, then you're going to have leakage issues soon no matter what oil you use. Switching to full synthetic in that situation will bring on more leakage sooner than using cheap conventional oils.

One other thing, If you see a lot of varnish and dark deposits when you inspect under the valve cover before changing over, you should use the best filter you can get, and change it at the standard filter change interval (even if it's an "extended performance" filter) for the first 2 or 3 filter changes. All that dark stuff will get washed away by the synthetic oil, and most of it it will land in your oil filter. What doesn't get to the oil filter will sit in the bottom of the oil pan, so don't be surprised by a bit of "heavy sludge" at the start of the drainage at your next oil change.

 

I agree with Richphotos. Oil is oil, your paying for the name. Also if your gaskets are bad they`re gonna leak anyway. And using a heavier weight oil can put strain on your oil pump causing it to fail early and destroy your engine.

 

Yes the characteristics of synthetic oil are well documented and I understand their use for severe cold starting, heavy loading and/or extended change intervals.

The notion of a late service life change has now brought out a debate about the potential negative effects of another characteristic being the sludge solvent effect. There is also cost if thats important (oil and filter)

My 2002 has 200,000 miles on PYB dino 5W30 in Florida with no trailer. Have the guys that have made a change to synthetic in situations like mine seen any difference in vehicle operation?

 

If this is completely warmed up (>20 miles) in hot weather with the AC on - 20 psi at 550rpm in drive is quite good - and a little over 40psi at 70MPH is also decent. I wouldn't sweat it unless it is dropping down well below 20psi at idle. That would indicate worn bearings and/or excessive clearances. Keep the 5W30 dino oil and change it often.


Les

 

Post # 5 Did you see any benefits in changing to synthetic oil in your high mileage vehicles?


The most visible difference I've noticed when switching high mileage engines to full synthetic oil is the size and amount of debris on the drain plug magnet. There's just a tiny amount of bearing material that looks like graphite. Much less with synthetic oil after 5,000 miles than regular oil after 2,500 miles. That surprised and convinced me.