diff --git a/doc/source/doxygen-docs/changelog.md b/doc/source/doxygen-docs/changelog.md
index f99bd00bc2..7a64c159d9 100644
--- a/doc/source/doxygen-docs/changelog.md
+++ b/doc/source/doxygen-docs/changelog.md
@@ -19,6 +19,8 @@
     - New method mrpt::gui::CGlCanvasBase::CamaraParams::FromCamera()
   - \ref mrpt_math_grp
     - Added missing method for consistent API across pose classes: mrpt::math::TPose3D::operator+()
+  - \ref mrpt_system_grp
+    - mrpt::system::COutputLogger::writeLogToFile() will now save *all* messages despite the runtime log verbosity level.
 - BUG FIXES:
   - Fix error rendering an opengl scene with mrpt::opengl::CCamera objects in it.
   - rawlog-edit silently ignored when more than one operation was requested.
diff --git a/libs/system/include/mrpt/system/COutputLogger.h b/libs/system/include/mrpt/system/COutputLogger.h
index e9bb6e9330..f6d15ca479 100644
--- a/libs/system/include/mrpt/system/COutputLogger.h
+++ b/libs/system/include/mrpt/system/COutputLogger.h
@@ -11,13 +11,16 @@
 
 #include <mrpt/core/Clock.h>
 #include <mrpt/system/CTicTac.h>
-#include <mrpt/system/os.h>  // for console color constants
+#include <mrpt/system/os.h>	 // for console color constants
 #include <mrpt/typemeta/TEnumType.h>
 
 #include <array>
 #include <deque>
 #include <functional>
 #include <iosfwd>
+#include <memory>
+#include <mutex>
+#include <optional>
 #include <sstream>
 #include <string>
 #include <string_view>
@@ -97,13 +100,16 @@ using output_logger_callback_t = std::function<void(
  *
  *   Default logging level is LVL_INFO.
  *
- * User may receive callbacks whenever a message is displayed to console by
- * using
- * logRegisterCallback(). If for some reason the callbacks are not needed any
- * more,
- * use logDeregisterCallback() to stop receiving calls. This mechanism is useful
- * in case of showing the messages to a GUI, transmiting them to a remote
- * machine, etc.
+ * User may receive callbacks whenever a message is *displayed to console* by
+ * using logRegisterCallback(). If for some reason the callbacks are not needed
+ * any more, use logDeregisterCallback() to stop receiving calls. This mechanism
+ * is useful in case of showing the messages to a GUI, transmiting them to a
+ * remote machine, etc.
+ *
+ * Note that only those messages whose "importance level" will be printed and
+ * sent to user callbacks. However, *all* messages will be stored and saved to a
+ * file with writeLogToFile() despite the current filter, if
+ * `logging_enable_keep_record` is set to `true` (Default=`false`).
  *
  * \note By default every logged message is going to be dumped to the standard
  * output as well (if VerbosityLevel > m_min_verbosity_level). Unset \b
@@ -143,17 +149,18 @@ class COutputLogger
 	 * a_logger.setLoggerName("logger_name");
 	 * \endcode
 	 */
-	COutputLogger(std::string_view name);
-	/** Default class constructor. Name of the logger is initialized to "logStr"
-	 */
-	COutputLogger();
+	COutputLogger(std::string_view name) : m_logger_name(name) {}
+
+	/** Default constructor	*/
+	COutputLogger() = default;
+
 	/** virtual dtor (so we can derive classes from this one) */
 	virtual ~COutputLogger();
 
 	/** \brief Main method to add the specified message string to the logger.
 	 * \sa logCond, logFmt */
 	void logStr(const VerbosityLevel level, std::string_view msg_str)
-		const;  // renamed from log() to avoid conflict with math ::log()
+		const;	// renamed from log() to avoid conflict with math ::log()
 
 	/** \brief Alternative logging method, which mimics the printf behavior.
 	 *
@@ -171,7 +178,7 @@ class COutputLogger
 	 * \sa logStr, logCond
 	 */
 	void logFmt(const VerbosityLevel level, const char* fmt, ...) const
-		MRPT_printf_format_check(3, 4);  // arg 1=this
+		MRPT_printf_format_check(3, 4);	 // arg 1=this
 
 	/** \brief Log the given message only if the condition is satisfied.
 	 *
@@ -220,7 +227,8 @@ class COutputLogger
 	 *
 	 * \sa dumpToConsole, getAsString
 	 */
-	void writeLogToFile(const std::string* fname_in = nullptr) const;
+	void writeLogToFile(
+		const std::optional<std::string> fname_in = std::nullopt) const;
 	/** \brief Dump the current contents of the COutputLogger instance in the
 	 * terminal window.
 	 *
@@ -307,9 +315,10 @@ class COutputLogger
 	std::string generateStringFromFormat(
 		std::string_view fmt, va_list argp) const;
 
-	std::string m_logger_name;
-	mutable std::deque<TMsg>
-		m_history;  // deque is better than vector to avoid memory reallocs
+	std::string m_logger_name = "COutputLogger";
+	// deque is better than vector to avoid memory reallocs
+	mutable std::deque<TMsg> m_history;
+	std::shared_ptr<std::mutex> m_historyMtx = std::make_shared<std::mutex>();
 
 	std::deque<output_logger_callback_t> m_listCallbacks;
 };
diff --git a/libs/system/src/COutputLogger.cpp b/libs/system/src/COutputLogger.cpp
index 80518f7eb8..23ff1dd58d 100644
--- a/libs/system/src/COutputLogger.cpp
+++ b/libs/system/src/COutputLogger.cpp
@@ -7,18 +7,21 @@
    | Released under BSD License. See: https://www.mrpt.org/License          |
    +------------------------------------------------------------------------+ */
 
-#include "system-precomp.h"  // Precompiled headers
-
 #include <mrpt/core/exceptions.h>
+#include <mrpt/core/lock_helper.h>
 #include <mrpt/system/COutputLogger.h>
 #include <mrpt/system/datetime.h>
-#include <cstdarg>  // for logFmt
+#include <mrpt/system/filesystem.h>
+
+#include <cstdarg>	// for logFmt
 #include <cstdio>
 #include <fstream>
 #include <iostream>
 #include <sstream>
 #include <vector>
 
+#include "system-precomp.h"	 // Precompiled headers
+
 #ifdef _MSC_VER
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>  // OutputDebugString() for MSVC
@@ -38,9 +41,9 @@ using namespace std;
 static std::array<mrpt::system::TConsoleColor, NUMBER_OF_VERBOSITY_LEVELS>
 	logging_levels_to_colors = {
 		CONCOL_BLUE,  // LVL_DEBUG
-		CONCOL_NORMAL,  // LVL_INFO
+		CONCOL_NORMAL,	// LVL_INFO
 		CONCOL_GREEN,  // LVL_WARN
-		CONCOL_RED  // LVL_ERROR
+		CONCOL_RED	// LVL_ERROR
 };
 
 std::array<mrpt::system::TConsoleColor, NUMBER_OF_VERBOSITY_LEVELS>&
@@ -54,7 +57,7 @@ static std::array<std::string, NUMBER_OF_VERBOSITY_LEVELS>
 		"DEBUG",  // LVL_DEBUG
 		"INFO ",  // LVL_INFO
 		"WARN ",  // LVL_WARN
-		"ERROR"  // LVL_ERROR
+		"ERROR"	 // LVL_ERROR
 };
 std::array<std::string, NUMBER_OF_VERBOSITY_LEVELS>&
 	COutputLogger::logging_levels_to_names()
@@ -62,30 +65,27 @@ std::array<std::string, NUMBER_OF_VERBOSITY_LEVELS>&
 	return ::logging_levels_to_names;
 }
 
-COutputLogger::COutputLogger(std::string_view name)
-{
-	this->loggerReset();
-	m_logger_name = name;
-}
-COutputLogger::COutputLogger() { this->loggerReset(); }
 COutputLogger::~COutputLogger() = default;
+
 void COutputLogger::logStr(
 	const VerbosityLevel level, std::string_view msg_str) const
 {
-	if (level < m_min_verbosity_level) return;
-
 	// initialize a TMsg object
 	TMsg msg(level, msg_str, *this);
-	if (logging_enable_keep_record) m_history.push_back(msg);
+	if (logging_enable_keep_record)
+	{
+		auto lck = mrpt::lockHelper(*m_historyMtx);
+		m_history.push_back(msg);
+	}
 
-	if (logging_enable_console_output)
+	if (level >= m_min_verbosity_level && logging_enable_console_output)
 	{
 		msg.dumpToConsole();
-	}
 
-	// User callbacks:
-	for (const auto& c : m_listCallbacks)
-		c(msg.body, msg.level, msg.name, msg.timestamp);
+		// User callbacks:
+		for (const auto& c : m_listCallbacks)
+			c(msg.body, msg.level, msg.name, msg.timestamp);
+	}
 }
 
 void COutputLogger::logFmt(
@@ -151,6 +151,7 @@ void COutputLogger::setVerbosityLevel(const VerbosityLevel level)
 void COutputLogger::getLogAsString(std::string& fname) const
 {
 	fname.clear();
+	auto lck = mrpt::lockHelper(*m_historyMtx);
 	for (const auto& h : m_history) fname += h.getAsString();
 }
 std::string COutputLogger::getLogAsString() const
@@ -159,23 +160,20 @@ std::string COutputLogger::getLogAsString() const
 	this->getLogAsString(str);
 	return str;
 }
-void COutputLogger::writeLogToFile(
-	const std::string* fname_in /* = nullptr */) const
+void COutputLogger::writeLogToFile(const std::optional<string> fname_in) const
 {
+	using namespace std::string_literals;
+
 	// determine the filename - open it
-	std::string fname;
-	if (fname_in)
-	{
-		fname = *fname_in;
-	}
-	else
-	{
-		fname = m_logger_name + ".log";
-	}
+	std::string fname =
+		fname_in.has_value()
+			? fname_in.value()
+			: mrpt::system::fileNameStripInvalidChars(m_logger_name) + ".log"s;
+
 	std::ofstream f(fname);
 	ASSERTMSG_(
 		f.is_open(), mrpt::format(
-						 "[%s:] Could not open external file: %s",
+						 "[%s] Could not open external file: %s",
 						 m_logger_name.c_str(), fname.c_str()));
 
 	std::string hist_str;
@@ -186,11 +184,13 @@ void COutputLogger::writeLogToFile(
 
 void COutputLogger::dumpLogToConsole() const
 {
+	auto lck = mrpt::lockHelper(*m_historyMtx);
 	for (const auto& h : m_history) h.dumpToConsole();
 }
 
 std::string COutputLogger::getLoggerLastMsg() const
 {
+	auto lck = mrpt::lockHelper(*m_historyMtx);
 	TMsg last_msg = m_history.back();
 	return last_msg.getAsString();
 }
@@ -200,18 +200,7 @@ void COutputLogger::getLoggerLastMsg(std::string& msg_str) const
 	msg_str = this->getLoggerLastMsg();
 }
 
-void COutputLogger::loggerReset()
-{
-	m_logger_name = "log";  // just the default name
-
-	m_history.clear();
-	logging_enable_console_output = true;
-	logging_enable_keep_record = false;
-
-	// set the minimum logging level allowed for printing. By default its
-	// LVL_INFO
-	m_min_verbosity_level = LVL_INFO;
-}
+void COutputLogger::loggerReset() { *this = COutputLogger(); }
 
 // TMsg Struct
 // ////////////////////////////////////////////////////////////
@@ -254,7 +243,7 @@ void COutputLogger::TMsg::dumpToConsole() const
 {
 	const std::string str = getAsString();
 
-	const bool dump_to_cerr = (level == LVL_ERROR);  // LVL_ERROR alternatively
+	const bool dump_to_cerr = (level == LVL_ERROR);	 // LVL_ERROR alternatively
 	// dumped to stderr instead
 	// of stdout