Hi everybody. I don't really know a whole deal on synth oil but I've got a question...
Last time I changed my trucks oil, one of the guys suggested I switch to synthetic just because (he says) it's better.
Here's some facts: I have an '05 QC, 5.7 Hemi with 60,000 miles. With this said...
1. Is synth oil really better? Does it noticeably improve anything?
2. Is it more expensive?
3. Are the intervals between changes longer?
4. I know you can't just "swith" oils, but you have to somehow "clean" the engine first?

These questions are probably too easy for you guys but I'm a rookie in these issues and I want to have a better engine and make it last longer if possible. Thanks.

I cannot speak for all of them but when I switched to AMSOIL 0w-20 it is good for 1 year or 25,000 miles...

quote:

Originally posted by Ric's new HEMI:
Hi everybody. I don't really know a whole deal on synth oil but I've got a question...
Last time I changed my trucks oil, one of the guys suggested I switch to synthetic just because (he says) it's better.
Here's some facts: I have an '05 QC, 5.7 Hemi with 60,000 miles. With this said...
1. Is synth oil really better? Does it noticeably improve anything?

Their claims are YES it is better. Check the manufacturer's web site for specifics.

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2. Is it more expensive?

Yes, you'll pay 2x-4x the cost for regular oils but, the extended drain rate will save money over the life of the oil change.

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3. Are the intervals between changes longer?

I use AMSoil 0w-30 Signature Series Oil (SSO) and drain rates are 1 year or 35k miles. You must also use the AMSoil oil filter(s) to get the extended drain rate of 35K miles. I sample my oil every 9-10K miles and send it in for analysis.

quote:

4. I know you can't just "swith" oils, but you have to somehow "clean" the engine first?

AMSoil has its own "Engine Flush" that must be used to clean the engine prior to your first AMSoil oil change. No need for repeated use with your next oil change.

quote:

These questions are probably too easy for you guys but I'm a rookie in these issues and I want to have a better engine and make it last longer if possible. Thanks.

If you have specific questions about AMSoil, send BigART a PM and he'll answer any question you have.

quote:

Originally posted by Ric's new HEMI:
Hi everybody. I don't really know a whole deal on synth oil but I've got a question...
Last time I changed my trucks oil, one of the guys suggested I switch to synthetic just because (he says) it's better.
Here's some facts: I have an '05 QC, 5.7 Hemi with 60,000 miles. With this said...
1. Is synth oil really better? Does it noticeably improve anything?
2. Is it more expensive?
3. Are the intervals between changes longer?
4. I know you can't just "swith" oils, but you have to somehow "clean" the engine first?

These questions are probably too easy for you guys but I'm a rookie in these issues and I want to have a better engine and make it last longer if possible. Thanks.

1 - Yes, synthetic oil is superior to conventional oil. Improved wear protection, improved flow at cold start, improved protection against thermal breakdown, superior detergents help to keep the engine cleaner, and you may even see a very slight gain in MPG( .5 MPG +/- ). Basically it is better in every aspect of oil.

2 - Yes, synthetic oil is more expensive than conventional oil. However, depending on what synthetic you buy it is not a lot more expensive. Premium/boutique oils like Royal Purple, Redline, Schaeffer's, and Amsoil are very expensive compared to conventional oil. Figure at least $7-$8+ a qt and generally more.

Now, if you go to Wal-Mart and buy in bulk 5qt jugs, or buy qts on sale at a parts store, the synthetics from the name brand companies such as Penzoil Platinum, Valvoline Synpower, Quaker State Ultimate Durability, Mobil 1, Kendall GT1, etc... you possibly will pay as little as $4 a qt( usually $5 +/- )which is not a lot more than conventional oil AND you may even get a filter to boot( example - PepBoys offered 5 qts of Kendall GT1 full synthetic with a store brand filter for $19.99 just a month or so back ). All depends on which synthetic you are talking about buying as to how much more $$$ it will be vs conventional oil.

The name brand oils like Penzoil Platinum, Valvoline Synpower, Quaker State UD, Mobil 1, Kendall GT1, etc... are all very good oils and unless you are going to run more than 10K on the oil are a much more cost efficient option than the more expensive super premium oils like RP and Amsoil.

3 - Yes, you can run synthetic oil longer than conventional oil. Most any quality synthetic is good for 10K at least. I wouldn't run the best conventional oil longer than 7500 max. Some synthetics are good for longer than 10K. In a healthy engine 15K is a realistic figure to expect from the better synthetics.

IMO however if you plan to run ANY synthetic oil over 6 months and/or 10-15K( max )you should only do so if a used oil analysis( UOA )has been done to make sure it is still capable of more service life. I do not buy into any oil being good for a guarateed time frame in months/years nor mileage. I definitely would not run a year and 25K+ on any oil. That is just me I know others will disagree.

10K is safe for most any synthetic but beyond that only a UOA will tell you for sure. Run any of the name brand synthetics for 10K intervals and you are safe "IN A HEALTHY ENGINE"!!!!!". If you have issues with oil contamination however ( ie; antifreeze leaking into the oil or you have issues with fuel dillution )10K is going to be too long. You need to get those things fixed anwyay but until then don't push it just because it is synthetic.

Also, not only will that oil protect the engine better than conventional oil but it will actually cost you less money vs changing conventional oil 2X's over that 10K. If you buy the more affordable name brand stuff anwyay.

One other important note. To go anything much over 7500 miles on your interval you need to run a filter capable of extended intervals( Royal Purple, Amsoil, K&N, Mobil 1 ). If you will run a regular filter like Wix/Napa Gold, Purolator/Bosch, MOPAR, Baldwin, etc... you really need to change the filter every 5K or so and then top off your oil. For 10K intervals the Royal Purple, Amsoil, K&N, and Mobil 1 filters will do it in one shot. The Royal Purple and Amsoil filters both should be able to handle up to 15K intervals. I would run no filter longer than 15K personally.

4 - Actually, you do not need to do a flush when swapping over to synthetic for the 1st time. Amsoil offers a flush and recommends it( all the time in every instance? )but they are the only ones I know of that do. You really don't need to do it unless it is a really high mileage vehicle with an unknown maintenance history and in that case I wouldn't make the swap anyway. That is asking for leaks and/or consumption issues to either worsen or develop as the detergents clean out all the internal deposits and expose weak areas.

The other oil companies basically say to just do it or to do a short interval and then change it before going to longer intervals. The reason being the superior detergents in synthetic will clean your engine out and can overload the filter.

Your truck has just 60K and if you have been good about regular OC's( 3-5K )with quality conventional oil then there is really no need to do anything but just swap over. To be safe you could do a shorter interval, or two, then go to whatever extended interval you want to run.

IMO buying any flush product before swapping over to synthetic is a complete waste of $$$. If it makes you happy though I am sure the Amsoil one is a quality product.

This message has been edited. Last edited by: NHHEMI,

Great feedback Mark & Scott

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IMO buying any flush product before swapping over to synthetic is a complete waste of $$$

I think your questions have been covered pretty well so I will add this for everyone.

Remember that most "full synthetics" are generally a group 3 oil which is still a petroleum base.

Look for "100% synthetic" which are generally your group 4 bases stocks (PAO) which is not petroleum.

You can use longer drain intervals with filters not designed to go longer. No trick involved either, just change your filter when your supposed to and top off the oil. For example, you don't have to use an AMSOIL filter with AMSOIL oil. You change the filter at every 3K, 5K or whatever your manufacture suggests and top the oil off. The oil is still good for the length of time AMSOIL recommends.


About engine flush. AMSOIL recommends if you have more then 15k miles to use the engine flush prior to switching, but it is not mandatory by any means. The engine flush helps get rid of sludge and deposits that have built up with lesser quality oils. Using the engine flush is less expensive then changing filters out sooner then needed due to them getting filled with crud.

When switching to synthetic it is important to keep an eye on your oil level for the next couple months, if you notice your oil level dropping then it's time to replace your filter and top off. Good synthetics in general have better detergents that will clean sludge and deposits away over time. Better synthetics like AMSOIL will never cause sludge or deposits.


No matter which oil or filter you choose make sure you follow the drain and filter change interval whether it be the car manufacturer or the oil manufacturer of the oil/filter. Don't guess on how long your oil will last based on opinions! If you choose AMSOIL then use AMSOIL's recommendations, if you choose other oil companies follow their recommendations, and if they have no guide for intervals then follow your owners manual.

If you want to go further then suggested intervals then perform oil analysis.

Hope this helps give you a little better understanding.

I just changed my oil at 32,000 miles, using the SSO 0W/30 product. Oil still looked good, but I changed it anyway. I have Amsoil's bypass filter on it so it gets double filtered, which I highly recommend if you are going to keep the truck for a long while. It really protects the oil and your engine.

Big Art... If I'm correct in what I've read doesn't Amsoil make two different levels of oil. One is for 7,500 miles and the next level is for 15,000....recommended.
In my 08 I use 5W20 for the MDS, and still change "about" every 8,000. The reason I say about is the 08's and newer tell you when to change the oil...msg comes across the odometer when it's time. Do you have any further recommendations?

Also how long is SevereGear good for in normal use, rear differential?

If you are using AMSOIL's XL; it is rated for 6 months or 7,500 miles and up to 12,000 miles for vehicles equipped with an oil monitoring device.

So if you change it at 8000 it's absolutely okay.

If you switch to the 0W-20 you can go 1 year or 25,000 miles. When the light comes on to change oil just reset it.

Severe Gear Lube under normal driving is good for 100,000 miles and 50,000 severe.