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Switching to Synthetic oil over 100K miles

7K views 11 replies 12 participants last post by  C66 Racing 
#1 ·
My 04 Escalade has over 100K and I have heard that switching to synthetic oil after you have a lot of miles will cause oil leaks and I have none now. Has anyone did this and had success? I just want ANY oil leaks and to keep my truck in tip top shape for a long time.
 
#4 ·
Ive been using synthetic since we purchased it used with 80k on the odometer. No leaks here. Not sure what the PO was using but the oil when I changed it was nice and clean. After 2k since oil change its still so clean its hard to see on the stick. Just do it and never look back. Your vehicle will love it.
 
#8 ·
I've been using castroil's synthetic product for a while now. I too have been going 5-8k between changes. I just keep an eye on the level (which has never been low ever after all those miles) and keep rolling. When the computer says it's time, I change it. It could probably go longer. The oil is usually just brownish at that point.
 
#10 ·
Unless you drive in Real Dusty Conditions often or do Alot of Idling - like in a Limousine Company - Anything less than 5,000 miles is a waste of $$$$$$. I have been told by the dealerships that you should trust the Change Oil Function and don't worry about the miles driven since the last oil change.
 
#11 ·
Trulytex said:
Unless you drive in Real Dusty Conditions often or do Alot of Idling - like in a Limousine Company - Anything less than 5,000 miles is a waste of $$$$$$. I have been told by the dealerships that you should trust the Change Oil Function and don't worry about the miles driven since the last oil change.
I live in a dusty area and use the oil life meter with no problems but I have noticed my air filter takes a hit with the dust but none gets past the filter(I get over 7,000 miles between oil changes)
 
#12 ·
My 04 Escalade has over 100K and I have heard that switching to synthetic oil after you have a lot of miles will cause oil leaks and I have none now.
There are many myths circulating regarding synthetic oils and seal leakage. Due to the significant variation in synthetic oil base stock (there are really three types on the market today), blanket statements about synthetic oils and seal leakage may be inappropriate. Many synthetics have a highly processed petroleum basestock (Group III basestock). Others use a PAO basestock (Group IV basestock), which tends to shrink seals. And yet others, such as Red Line use an ester basestock (Group V) which tends to swell seals. Most synthetics contain higher levels of detergents, which will clean sludge from seals exposing them to oil.

Most synthetics contain higher levels of detergents, which will clean sludge from seals exposing them to oil. Companies such as AMSOIL add a small percentage of Group V ester basestock to their oils to counteract the impact of seal shrinkage caused by PAO basestock. The result is a fluid that will actually slightly swell seals (on the order of a few percent). But, if the seals are dried and cracked and the higher levels of detergents in the synthetic cleans the sludge exposing these dried and cracked seals to oil, it will likely leak. For those that have never used synthetic and may have really old seals, you might want to stay away from synthetics. For others, who kept their oil clean and prevented sludge buildup, synthetics shouldn't negatively impact your seals.

If you have a clean engine and you are experiencing no leaks, then you should not have any leaks with AMSOIL or other quality synthetics. On the other hand, if the engine contains sludge due to age or inappropriate maintenance practices, you may experience a temporary leak. When the seals have gone for sometime without oil contacting and nourishing the seals due to blockage from sludge, they will harden and shrink. Since most synthetics, including AMSOIL, contain a significant amount of detergents, they will clean and remove this sludge exposing dried out seals to the oil. Depending on the synthetic oil used, this leakage may or may not be temporary. AMSOIL uses other additives such as Ester which will improve the seal’s suppleness and counters the shrinkage of the PAO basestock. But, if the seal has a mechanical fault, such as a crack or tear, then AMSOIL or other good synthetics can't repair the damage. How other synthetics effect the seals is highly dependent on their basestock. :cheers:
 
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