motor oil
Posting Guru
Joined: Nov 2011
Posts: 1,302
Likes: 5
From: Burlington, WI
To my understanding, synthetic oil is thinner than standard oil. Our older engines do not have as tight of tolerances internally to keep the thinner oil inside them, hence why they will leak if ya put that synthetic oil in em.
Fleet Mechanic
Joined: Feb 2011
Posts: 1,410
Likes: 42
From: Michigan
Why not use what is recommended for your differentials, trans, and motor oil. Got to remember this stuff was engineered almost 40 years ago when there wasn't synthetics around. Most have lasted this long. Waste of money to put in these old trucks. My 3 cents anyway.
Fleet Mechanic
Joined: Feb 2011
Posts: 1,410
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From: Michigan
X2 on Rotella for my flat tappet 390.
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Posting Guru
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Synthetic oils are not thinner than organic oils. 30W is 30W no matter what type oil it is. However, synthetics clean old deposits out of engines, such as carbon and sludge, and can attack old gasket material.
If your engine is already pretty well worn, going to a synthetic oil won't help it, and it may cause it to start smoking or using oil because it will clean the engine so well inside. If you have a low-mile engine and want to run synthetic there is nothing wrong with using it.
Running synthetic gear oil in a differential or standard transmission wouldn't hurt anything either, especially if you do a lot of heavy towing. The synthetic holds up to the extreme pressure and higher temps a bit better than organic.
If your engine is already pretty well worn, going to a synthetic oil won't help it, and it may cause it to start smoking or using oil because it will clean the engine so well inside. If you have a low-mile engine and want to run synthetic there is nothing wrong with using it.
Running synthetic gear oil in a differential or standard transmission wouldn't hurt anything either, especially if you do a lot of heavy towing. The synthetic holds up to the extreme pressure and higher temps a bit better than organic.
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Cross-Country
Joined: Jan 2014
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Oh come on with the oil nonsense guys. Synthetics do not 'clean' the inside of an engine. Synthetics have a higher lubricity than standard, and the reason you will get leaks is not because synthetic oil is cleaning, attacking, or whatever other myths people tend to share about motor oil.
There is ONE reason, and ONE reason only for leaks resulting from the use of synthetic: Motor oil derived from crude oil has an irregular molecular structure, whereas synthetic is relatively perfect, and thus, even at the same weight, synthetics flow better because the molecules are smaller.
Because synthetic does not break down like regular oil, you don't get the same sludge, etc. It is that sludge which over time will literally 'plug' leaks, and when you later switch to synthetic, the finer molecular structure is able to flow around and through those deposits.
Stick with regular oil(literally, the brand does not matter) changed at reasonable intervals, use good filters, and ignore the goofiness about zinc content, OMG Shell rotella!, crazy high oil weights, etc.
There is ONE reason, and ONE reason only for leaks resulting from the use of synthetic: Motor oil derived from crude oil has an irregular molecular structure, whereas synthetic is relatively perfect, and thus, even at the same weight, synthetics flow better because the molecules are smaller.
Because synthetic does not break down like regular oil, you don't get the same sludge, etc. It is that sludge which over time will literally 'plug' leaks, and when you later switch to synthetic, the finer molecular structure is able to flow around and through those deposits.
Stick with regular oil(literally, the brand does not matter) changed at reasonable intervals, use good filters, and ignore the goofiness about zinc content, OMG Shell rotella!, crazy high oil weights, etc.
Postmaster
Joined: Jan 2013
Posts: 3,512
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From: Panama City
I run Mobil 1 synth in my 78 Bronco. Inside of my engine is CLEAN. If I were to pull the valve cover today I guarantee it will look like it has just been rebuilt. So dont give me any B.S. about synthetic oil in old engines. I know it works and works well. Runs cooler, cleaner and oil change intervals make it very cost effective. If you have an oil leak, change the friggin gasket. I have run synthetic oil in all my old vehicles for at least 20 years. Never had any problem. And as stated above, they are clean inside. Period.
Post Fiend
Joined: Oct 2009
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From: town of less than 200 ppl
X3 for rotella. It's what I run in my 429 thunderjet, plus I get it from work for free.
Postmaster
Joined: Sep 2013
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From: Pasadena, Ca
So, to summarize...
Use what you want. And if you think that synthetic oil will make a difference in your truck that has probably been running on nonsynthetic for almost 40 years, and probably has not had regular 3month/3,000 mile oil changes, so be it.
I do think that when one of us buys a truck and starts taking care of it as we should, that regular oil changes of any type WILL start cleaning out sludge and make cause oil to flow better and leaks to form. When our POs didnt take care of it, they simply started driving it slower and less often.
Thats all i got...
Use what you want. And if you think that synthetic oil will make a difference in your truck that has probably been running on nonsynthetic for almost 40 years, and probably has not had regular 3month/3,000 mile oil changes, so be it.
I do think that when one of us buys a truck and starts taking care of it as we should, that regular oil changes of any type WILL start cleaning out sludge and make cause oil to flow better and leaks to form. When our POs didnt take care of it, they simply started driving it slower and less often.
Thats all i got...
Junior User
Joined: Dec 2013
Posts: 80
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From: MT - The Last Best Place
3 month/3,000mi intervals are too frequent in my opinion. Most vehicle manufacturers recommend between 5,000 and 7,000 anything sooner than that (in normal driving conditions) is wasting money. RumRunner78 is correct, but...
Before throwing any type of oil in there, I would read up on http://en.wikipedia.org/wiki/Zinc_dithiophosphate or "ZDDP" (why everyone here swears by Rotella-T)
I hope this thoroughly answers your question.
Before throwing any type of oil in there, I would read up on http://en.wikipedia.org/wiki/Zinc_dithiophosphate or "ZDDP" (why everyone here swears by Rotella-T)
taken from zddp.com
"According to the SAE Tech Bulletin # 770087 [1] , operation of a flat tappet engine without adequate EP additives such as ZDDP quickly leads to lifter foot scuffing and cam lobe wear. Camshafts are typically only surface hardened leaving the core ductile for strength. According to the SAE Bulletin, once cam lobe wear reaches 0.0002, "subsequent wear is usually rapid and catastrophic." Two ten-thousandths of an inch is one fifth the thickness of an average human hair.
In order to make engines last in the absence of ZDDP, virtually all IC (internal combustion) engines designed in the last ten years utilize roller lifters. Today, ZDDP has been removed from practically all automotive engine oils, rendering them unsuitable for use with older engines with non-roller lifters."
Why Can't We Use Diesel CI/CJ-4 Rated Oils?
"There are some diesel engine rated oils on the market which may still have some ZDDP in them. There are problems associated with using these oils in a normal gasoline engine which can become severe in a high-performance gasoline engine. One issue is the high amount of detergent additive, and another is the high viscosity.
High detergent oil has a lower surface tension and lower shear pressure rating which can cause higher bearing wear in gas engines. A diesel engine needs oil with very high detergent capabilities in order to hold the large amount of combustion byproducts in suspension, but it is not optimized for a gasoline engine. The bearing journal size-to-displacement ratio on a gasoline engine is designed around the use of a lower detergent oil and relies on a high-shear rating to the oil.
The other problem with high detergent oil is that it actually reduces the friction reduction that the ZDDP affords, especially in a high-performance, high valve spring pressure engine.
The viscosity rating of most diesel rated oils is higher than optimum for our higher revving gasoline engines, and can cause oil starvation in bearings at high rpms."
Why Can't We Use Racing Oils?
"There are some racing oils which maintain a level of ZDDP. Racing oils are optimized for short term severe duty, in contrast to an oil that has been designed for day in, day out street operation. The additive package in a racing oil does not have the same detergent characteristics which are designed into extended service oils. As a result, racing oils may not have the capability of neutralizing acids and keeping contaminants in suspension. Also, the breadth of choice of viscosity, so important to correct street engine operation over a broad temperature range, is not available in racing oils.
By using ZDDPlus™ in addition to a modern high-quality oil of the proper viscosity for your gasoline engine, the correct EP lubrication level is established, and the oil characteristics remain optimized for your engine.r engine."
What if my oil already has some ZDDP?
"ZDDP is most effective if the concentration is between 0.18 and 0.2 % by weight. Tests have shown that concentrations above this amount, up to as much as several percent, have no effect except to prolong additive life. The current oils available today contain very little ZDDP."
Aren't the newer oils better than the older oils?
"Historically, every new grade of oil introduced since the 1930's was better than the previous grade and could be considered "improved" with one exception. The original SA grade was straight mineral oil (non-detergent non-additives) and SB contained additives which could not be used in the earliest cars specified for SA. While it is true that SM oils are better for NEW cars, they are NOT better for the OLDER cars equipped with flat tappet camshafts. Simply put, the newer, better oils are not backward compatible for older cars primarily due to the gradual reduction of ZDDP starting with SG grade introduced in 1988. In the next few years, it will be eliminated completely from oil."
cheers
"According to the SAE Tech Bulletin # 770087 [1] , operation of a flat tappet engine without adequate EP additives such as ZDDP quickly leads to lifter foot scuffing and cam lobe wear. Camshafts are typically only surface hardened leaving the core ductile for strength. According to the SAE Bulletin, once cam lobe wear reaches 0.0002, "subsequent wear is usually rapid and catastrophic." Two ten-thousandths of an inch is one fifth the thickness of an average human hair.
In order to make engines last in the absence of ZDDP, virtually all IC (internal combustion) engines designed in the last ten years utilize roller lifters. Today, ZDDP has been removed from practically all automotive engine oils, rendering them unsuitable for use with older engines with non-roller lifters."
Why Can't We Use Diesel CI/CJ-4 Rated Oils?
"There are some diesel engine rated oils on the market which may still have some ZDDP in them. There are problems associated with using these oils in a normal gasoline engine which can become severe in a high-performance gasoline engine. One issue is the high amount of detergent additive, and another is the high viscosity.
High detergent oil has a lower surface tension and lower shear pressure rating which can cause higher bearing wear in gas engines. A diesel engine needs oil with very high detergent capabilities in order to hold the large amount of combustion byproducts in suspension, but it is not optimized for a gasoline engine. The bearing journal size-to-displacement ratio on a gasoline engine is designed around the use of a lower detergent oil and relies on a high-shear rating to the oil.
The other problem with high detergent oil is that it actually reduces the friction reduction that the ZDDP affords, especially in a high-performance, high valve spring pressure engine.
The viscosity rating of most diesel rated oils is higher than optimum for our higher revving gasoline engines, and can cause oil starvation in bearings at high rpms."
Why Can't We Use Racing Oils?
"There are some racing oils which maintain a level of ZDDP. Racing oils are optimized for short term severe duty, in contrast to an oil that has been designed for day in, day out street operation. The additive package in a racing oil does not have the same detergent characteristics which are designed into extended service oils. As a result, racing oils may not have the capability of neutralizing acids and keeping contaminants in suspension. Also, the breadth of choice of viscosity, so important to correct street engine operation over a broad temperature range, is not available in racing oils.
By using ZDDPlus™ in addition to a modern high-quality oil of the proper viscosity for your gasoline engine, the correct EP lubrication level is established, and the oil characteristics remain optimized for your engine.r engine."
What if my oil already has some ZDDP?
"ZDDP is most effective if the concentration is between 0.18 and 0.2 % by weight. Tests have shown that concentrations above this amount, up to as much as several percent, have no effect except to prolong additive life. The current oils available today contain very little ZDDP."
Aren't the newer oils better than the older oils?
"Historically, every new grade of oil introduced since the 1930's was better than the previous grade and could be considered "improved" with one exception. The original SA grade was straight mineral oil (non-detergent non-additives) and SB contained additives which could not be used in the earliest cars specified for SA. While it is true that SM oils are better for NEW cars, they are NOT better for the OLDER cars equipped with flat tappet camshafts. Simply put, the newer, better oils are not backward compatible for older cars primarily due to the gradual reduction of ZDDP starting with SG grade introduced in 1988. In the next few years, it will be eliminated completely from oil."
cheers
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