Oil change intervals for synthetic oil

[tontod]

I know for regular oils, oil changes are recommended at 3k miles. Someone told me its longer if you use synthetic oils. Is that true?

 

[The Stigenator]

synth oils can go upto 7000miles between changes.

 

[Tominator]

Here is something that has solidified my opinion of synthetics or in this case a blend...

This was in a Detroit Diesel 60 series. Class 8 truck or a 'Semi' for most. Now, realise that a large diesel runs closer to it's design limitations than an automobile ever will this side of racing...

Includeing the first oil, the engine was run for 1 million miles. That's right! On 3 oil changes!

The only problem encountered was that the oil filter was not up to the task. It was changed every 100,000 miles...

The motor was torn down by someone I know and only showed normal wear!

A conventional oil change with normal oil is every 16,000 miles.

The disasembled motor was shipped to Detroit Diesel and the engineers there were absolutly amazed. The motor was rebuilt and put back in service....now, get this....the crank was NOT reground!!!

I just rebuilt my 5.0 Ford Truck motor of 1985 vintage. After 2500 miles on 10X40 WalMart oil it has not used oil in 1000 miles. It's getting 10w30 Walmart Synthetic Blend and I'll run it for 5000 miles using Fram's new filter that is supposed to filter a smaller micron particle. I'll evaluate after the 5000 miles and decide if more milage can be run between changes.

Be aware that extended oil changes must fall within recomendations of the vehicle manfacturer to keep your warranty.

 

[Telemonius]

i would agree and say 7,000 is about right. honestly, it could be more i'm not sure. it's nice to have in high-performance engines, esp. turbo/supercharged cars and trucks. it's more resistant to breaking down (from high heat) compared to regular oil.

 

[killmeplease]

Spin on a new GOOD filter every 3000 and change at 9000.

And use one of the better synths. Amsoil or Mobile One.

 

[Hoeboy]

did they recently advertise this special synthetic oil that can supposedly go up to 150,000 miles? it was called synguard or something like that. supposedly NASA technology.

 

[killmeplease]

One of the biggest factors in synth oil is the quality of the additives.

I can't imagine going over 25000 mi on a change. Sometimes you just have to change the oil to get the dirt out and a filter will not get the unspent gas out.

 

[freebee]

Under low stress conditions (highway driving and moderate temperatures) there is very little wear on the engine or the oil, synthetic or dino juice. Synthetics give you added insurance in variable temps (high heat, cold start, etc. ) applications, but does little in terms of extending oil life in normal driving. Use a name brand oil of correct viscosity and you will be fine. I personally use Mobil 1 and have had good results, especially during cold weather starts.

 

[Evadman]

It's your favorite neiborhood tech again, dont sue me.

The only reason that you change the oil in a car is because over time it will break down. A synthetic will break down VERY slowly. Organic oil, or STD oil, loses it's "slippryness" over tiem from thermal break down and from actually being cut in 1/2 by rotating parts. Synthetic is not harmed my "normal" operating temps, only by being cut up. If you have a car that is out of warantee, then you can go about 50,000 miles without changing the oil, bit you DO have to chage the filter. The filter takes out all the crap that gets in your oil ( casting samd, ash, ect ) and keeps it from harming your engine. A safe bet would be to chage your oil filter every 7-10k miles for reg driving, or every 3k for serous driving ( towing, off road, short trips, ect )

If it is in warantee, then no matter what, you have to chage it at the interval in your manual. Every vehicle is different. For example, here are some that I know.

Suzuki Sidekick 1.6 = 7500 miles
Dodge 2500 V-10 8.1 = 6000 Miles
S10 4.3 V6 = 10,000 miles

The only reason to change your oil in 3000 miles is if you do towing, short trips, snowplow, off roading, ect.

I am a tech at a dodge dealership, so I do know what I am talking about

 

[Tominator]

I've been somewhat involved in this subject since 1973 and have evaluated Mobil 1 and other oils under racing and normal driving.

The only way a modern 'oil' wears out is it's 'sheer strength.'

When oil is scraped from the piston walls the molecules are 'torn' by this action. The ability of an oil to resist this action is it's 'sheer strength.'

ALL modern oils have an excellant resistance to the molecules being torn apart. The other job oil does is to keep solids in suspension. A good filter can reduce the amount of these solids held in suspension.

Another way an oil can contribute to it's life is the ability for it to neutralise acids. These acids are mostly from gas contimination or the 'blow by' that the piston rings allow into the crankcase.

ALL modern oils are highly resistent to acid.

The only advantage that synthetics or synthetic blends contribute is in the sheer strength. If the acids and solids are at a minimum there is no reason to change oil at all if the sheer strength can be maintained.

One additional negative to a pure synthetic is the buildup of carbon in the combustion chamber but only at extended milage intervals and for most motorists that is never a problem.

I'll try the blend.

 

[FelixDeCat]

Been using Mobil 1 and changed every 6k. Stopped doing this a few cars ago when I started buying new and went with full dealer service to maintain warranty.