Synthetic oil

[microAmp]

I've been using the regular kind of oil in my GMC truck 4.8L V8 and currently have 38k miles. If I switch to synthetic oil can that cause any harm to the engine? I don't plan to flip back and forth, just stay with synthetic oil. Also that should be changed every 7,500 miles, right?

Thanks all.

 

[Ladies Man]

if you do it you need to have the old oil flushed out properly

you can't just drain regular oil and change it to synthetic

synthetic oil will last significantly longer. 7500 mile changes are good. I'm still a nut though and change mine at 3000miles cus i ride my car hard and its got 102k miles on it

 

[woodie1]

The two oils mix just fine. No need to flush anything. Your engine is young enough that you should have no problems.

 

[Don Vito Corleone]

<< if you do it you need to have the old oil flushed out properly

you can't just drain regular oil and change it to synthetic

synthetic oil will last significantly longer. 7500 mile changes are good. I'm still a nut though and change mine at 3000miles cus i ride my car hard and its got 102k miles on it >>



Actually you can just drain your oil and switch - all major brands of full-synthetic oil are compatible with regular petroleum-based oil.

I use full-synthetic and change it every 5,000 or so, but a friend used to drive a Camry with 220,000 miles that had a diet of full synthetic and had its oil changed only once a year (at roughly 20,000 intervals!) and it was going strong with no overhauls or other engine work. Obviously I can't recommend this maintenance plan, but mighty impressive nonetheless.

 

[microAmp]

<< The two oils mix just fine. No need to flush anything. Your engine is young enough that you should have no problems. >>



That I know you are correct on, was over at Yahoo's car guide and came across the synthetic oil and said you could mix the two without any worries.

I think I'm going to switch soon, just tired of changing it every 3k miles. Also, can use the same oil filter as the regualr oil? And when dumping the oil can you dump it in the same place where regular oil gets dumped?

 

[woodie1]

The same filters are generally okay. Don't know about disposal though.

 

[Thegonagle]

<< you can't just drain regular oil and change it to synthetic >>



Why's that? It's not like they formulate the synthetic stuff expecting people not to change their oil from regular to synthetic.

What do you ?flush? the engine with? Some $29 magic flush product?

Oh well, I?d only use synthetic if I had a turbocharged engine. My old car (An Accord, if you want to know) was burning almost no oil with 247,000 miles on it. I had records from the dealership of every service ever performed on that car. It never saw synthetic oil. Regular oil is just fine.

 

[fastz28]

Yeah, no need to flush, just change to synthetic next time.

It's ok to change at 7500 or more miles, but I would change the filter in between oil changes e.g. at 3750 miles.

 

[microAmp]

<< Yeah, no need to flush, just change to synthetic next time.
It's ok to change at 7500 or more miles, but I would change the filter in between oil changes e.g. at 3750 miles. >>



Hmm.... unfortnley the oil filter sits undeath the the entire engine and is right next to the oil drain plug, sitting vertically. I like the setup and don't, messy when taking if off after an oil drain.

 

[Ladies Man]

Here is a proper engine flush procedure when switching from petro-oil to syn-oil:

Engine flush cleans the internals of the engine and helps to flush out the old oil inside the engine and prepare the engine for synthetic motor oil. It cleans the crankcase, cylinder walls, pistons and rings for maximum efficiency and power.

Using engine flush will also prevent oil burning problems. An engine that has been using petroleum for a long while will have petroleum oil sludge accumulated inside the engine. Synthetics are naturally detergent, which will remove this sludge. However, this can cause the oil filter to become plugged with sludge and then the oil filter bypass relief valve opens, allowing unfiltered oil to circulate throughout the engine. This then allows dirty oil to be splashed up onto the cylinder walls interfering with efficient piston ring sealing, with the result that that rings don't seal as well with dirt in the oil and the rings let oil get by them into the combustion chambers, and presto, oil burning! Using engine flush will prevent this problem.

Engine flush is installed into the engine via the oil add/fill hole in the engine that you normally use, with the *old engine oil* still in the engine. You will need to drain off enough of the old oil to accommodate the addition of the engine flush, (one pint), to the engine oil, so as not to overfill the engine oil level. The easiest and most effective way to do this is by removing the old oil filter, and installing a new oil filter. This will remove enough of the old oil to accommodate the volume of the engine flush. The new filter will help remove any contaminants the engine flush removes far better than the old oil filter can that has already reached the end of its service life and is no longer is able to filter out contaminants like it did when it was new.

A. Do not drive the car, or put the transmission in gear with engine flush in the engine.

B. Having removed the old oil filter and installed a new oil filter, (don't use your oil filter for this, just get an inexpensive oil filter for the engine flush), pour in the entire contents of the can of engine flush into the engine oil fill hole.

C. Start the engine and run it at fast idle for fifteen to twenty minutes, then shut off the engine.

D. While the engine is still hot, drain the old oil from the engine. If you can, allow at least 30 minutes for the old oil to drain out of the engine. You would be surprised how much additional old oil can drain out of an engine in 30 minutes. I have seen an additional 1/2 quart of old oil drip out of an engine in 30 minutes of draining. The more of the old oil you can let drain out of the engine, the better your synthetic motor oil can perform for you. The more old oil you can drain out of the engine, the better.

E. Remove the oil filter you installed for the engine flush and install your new oil filter, tighten the oil pan drain plug, then add your synthetic motor oil to the engines proper fill level, start the engine and let it run for about 30 seconds, then shut if off and recheck the oil fill level on the dipstick and add any oil needed to top the oil level off.



but hey... who the hell am i to say what is right or wrong for your engine

 

[Thegonagle]

<< A. Do not drive the car, or put the transmission in gear with engine flush in the engine. >>



That, right there, tells me not to put it in the engine at all. Sounds scary.

 

[microAmp]

Thanks Ladies Man very informative!

 

[Soybomb]

A flush is not required and most mechanics I know think very little of any flushes. Synthetic oils will slowly over time break down sludge and deposits and clean your engine out. If you're concerned change you oil more frequently after you switch. Oil flushes on the other hand try to break the chunks out all in one piece. Which do you think is better a few very tiny pieces breaking off at a time or a large piece breaking off and trying to travel around. I've known people who have had clogged passages from using flushes and also one guy who had a chunk break off from around the crank and clog the screen of his pump starving his engine of enough oil. Before you flush ask your mechanic or the manufactuere (IE: mobil for mobil 1 synthetic) if a flush is necessary.

 

[Don Vito Corleone]

Keep in mind the procedure provided by Ladies Man was obviously written by a company that produces and sells an engine-flush product. Since your truck has only 38K miles, as long as it has had its oil changed regularly I am highly skeptical of whether the engine flush would add any value to the process.

 

[Ladies Man]

yes the info appears to be written by a company but i got it from a mechanic that i would trust my life with
the guy knows his stuff

 

[Dhawk]

I was listening to Larry Perry "The Magic Mechanic" on the radio yesterday, talk about this very topic. He is an Amsoil synthedic oil dealer also. He said that it is only necessary to flush an engine if it has high mileage or has not had regular oil changes, when changing over to Synthedic oil.

He also mentioned instead of using Amsoil's engine flush, to use Amsoil's atf fluid as a flush. The directions for using the atf that he gave were similar to what Laidies Man posted above. He said that you would be amazed at how much gunk and residue the atf would break up after you use it as a flush and then drain the oil.

 

[yellowvespa]

wow .. long post.

I'm retired now and from 35 years of playing with engines of all sorts, old and new, street and race, I will say this. I will never and most of the people I know in the automobile repair/race area will never flush a used engine.

When you add an oil flush and let it "clean " the inside of an engine, you will never get all of the scale, sludge and deposits that get loosened up to drain out. They are now floating around. Carbon is a very hard material. Hard enough to damage bearing babbit, cylinder walls, even a hardened crankshaft. Some people say that the filter will stop it from circulating. Wrong. The filter only stops what goes through it and depending on the brand, may not stop much at that. The oil and loosened crap can splash around for months and never get picked up by the oil pump to be drawn through the filter!

What I'm trying to say is that there is no reason to flush an engine. If it has had decent oil changes it's just fine in there and what did get deposited, well just leave it there. Don't look for trouble. I have seen many oil related failures after an oil flush.

On the synthetic thing. Yeah, nice slippery oil but do you really need it? I use Castrol or Vavoline, change it every 3K along with the filter and I'm pushing 215,000 on the original engine. As long as you change the oil often be it synthetic or petroleum based, you'll be just fine. They both get contaminated so longer intervals is a myth with synthetics.

 

[Ladies Man]

The major benefit of synthetics is that the manufacturer can control the purity of the oil. Well made synthetics do not contain undesireable hydro-carbon compositions (like tars). Frequent oil changes are necessary with dinos, but not so with synthetics since the "undesireables" aren't present and, therefore, can't break down into dirty, harmful pollutants through normal use. However, all oils including synthetics will break down over time and the lubricating properties will deteriorate.

Syn-oils will also run cooler and allow for slightly better fuel mileage.



<< Arent you supposed to change your oil because it is DIRTY. Dosent synthetic oil get just as dirty as conventional oil? >>


The higher quality synthetic oil filter such as the Amsoil product does a better job of filtering out the particles and contaminents. The synthetic oil doesn't break down like petroleum oils do so it will last much longer.

 

[Pliablemoose]

Another issue about switching back & forth is seal leakage, synthetic & conventional oil swell the seals of an engine @ different rates, if you switch, you'll get leaks more often than if you stay with one or the other... particularly in older engines.

 

[Ladies Man]

synthetics have smaller molecules and synthetics will not swell o-rings and gaskets as much as dinos. Therefore, synthetics have a tendency to find existing leaks, but don't cause them. Also, synthetics act as a dissolver so it will remove dirt and such that could have been preventing a leak.

 

[KokomoGST]

Change every 7500 miles? Well, it really does depend on the kind of driving you're doing. I change 2-3 times during fall-winter and ~4 during spring and summer because I do hard driving during those seasons (autoX, etc). (I don't drive for commute)

Synth on you engine should be fine, you're broken in and I doubt the seals in your engine will be flushed out. Synth is proven to be better than conventional for the pour qualities, resistance to change in chemical composition that leads to deposits. However, some people I've talked to insist that conventionals have much better shock protection your crank, bearings, etc. I don't know if there's hard data for that, but they're pretty knowledgeable folks. Just remember to not skimp on the filter and do not... do NOT buy a crappy Fram filter...

 

[microAmp]

<< Change every 7500 miles? Well, it really does depend on the kind of driving you're doing. I change 2-3 times during fall-winter and ~4 during spring and summer because I do hard driving during those seasons (autoX, etc). (I don't drive for commute)

Synth on you engine should be fine, you're broken in and I doubt the seals in your engine will be flushed out. Synth is proven to be better than conventional for the pour qualities, resistance to change in chemical composition that leads to deposits. However, some people I've talked to insist that conventionals have much better shock protection your crank, bearings, etc. I don't know if there's hard data for that, but they're pretty knowledgeable folks. Just remember to not skimp on the filter and do not... do NOT buy a crappy Fram filter... >>



I've been sticking with ACDelco filters since that is what was on the truck originally. Another thing was when I was in Hi-Lo one day one of the guys there said another GMC truck driver was using Fram and it screwed up his engine. Apparently ACDelco can do something that the Fram can't, can't think of the term right now, but like provide oil to other higher parts of the engine....

 

[Thegonagle]

Re: Oil filters.

The deal isn't that AC Delco is great, but that Fram is pure, total, crap. It's poorly built out of cheap materials and doesn't perform properly.

Someone posted a link to a page of a guy who dissected the filters made for his Mustang 5.0, and told us which brands to avoid. I'm in too much of a hurry to find it now, but I will later if no one else has it when I'm done working.

 

[Tominator]

So much crap and so little time.....

There is no such thing as 'flushing' a motor! That is a lame attempt to sell you something....

Oil needs changed not because it gets dirty, but because it loses 'sheer strength.' That is the action of the metal surfaces of the engine tearing apart the molecules in the oil that provide lubrication.

A syntheyic oil is superior in it's resistance to this.

The company I work for ran a 12.7 Litre Detroit Diesel in a truck for 1 million miles...without an oil change! The oil was a part synthetic as pure synthetic leaves carbon buildup. The filter was monitored and changed on an as needed basis. The motor was torn down and had minimul wear, sent to Detroit Diesel for analysis. They were amazed! The motor was rebuilt WITHOUT grinding the crankshaft and returned to service.

I use Castrol part synthetic and a premimum 10 micron filter. As long as you switch to a synthetic before 50,000 miles you should see no problems. Even if you do it will mean at most an extra quart between changes. I change my highmilage cars @3000 miles and use conventional oil and my Ford 302 motor I rebuilt @5000 miles and it gets the blend.